summary of topics 00:51 Structure of Atoms The session begins by emphasizing the importance of understanding history to grasp the structure of matter. It highlights Dalton's theory, which presented three key points, notably that matter is composed of indivisible elements, referred to today as atoms. Specifically, it denotes that each element, like sodium with 11 atoms, is defined by its unique atomic configuration. 01:43 History of Atomic Theory Sodium atoms in different cities possess the same structure, with each retaining 11 electrons. When sodium combines with chlorine, it forms sodium chloride, resulting in a new substance. Regarding Thomson's theory, it is considered 50% successful due to its contributions and limitations in atomic discovery. 02:49 Dalton's Theory थॉमसन ने कैथोड रे एक्सपेरिमेंट के माध्यम से इलेक्ट्रॉनों का पता लगाया, जो एक सफल खोज थी। उसने प्लम पुडिंग मॉडल पेश किया, जिसमें उसने इसे वाटरमेलन की संरचना के समान रखा, जहाँ आतम का पूरा हिस्सा सकारात्मक चार्ज के समान है। इस मॉडल ने परमाणु की संरचना को एक नया दृष्टिकोण प्रदान किया। 03:45 Thomson's Theory The watermelon serves as an analogy for atomic structure, illustrating that the body of the watermelon represents the positively charged atom, while the seeds symbolize negatively charged electrons. According to J.J. Thomson, the atom is primarily positive with negatively charged electrons embedded within it, yet the overall atom is electrically neutral. This clarification challenges the notion of a purely positively charged atom. 04:36 Plum Pudding Model Atoms are electrically neutral, containing an equal number of positively charged protons and negatively charged electrons. The electrons orbit the nucleus, and the failure of the Plum Pudding Model is demonstrated through experiments like the Cathode Ray Experiment, which indicated the existence of electrons as negatively charged particles attracted to positive charges. Rutherford's Gold Foil Experiment further challenged the Plum Pudding Model, leading to the understanding of the atom's structure. 08:39 Rutherford's Gold Foil Experiment Rutherford's gold foil experiment demonstrated that while most alpha particles passed through gold foil without scattering, a small fraction were deflected, leading to the conclusion that atoms are mostly empty space with a dense nucleus at the center. This realization highlighted that 99.9% of the atom's volume is unoccupied, underscoring the significant difference between the size of the nucleus and the atom itself. Additionally, the experiment raised questions about the stability of the atom and the behavior of electrons around the nucleus. 20:18 Atomic Spectra Atomic spectra arise when electrons transition between energy levels within atoms, releasing or absorbing energy in the process. This was illustrated in a memorable class trip to Gajanan Market, where students used a spectrometer to observe various light sources, leading to a humorous incident with shopkeepers who thought their crowd was suspicious. There are two types of spectra: emission spectra, where energy is released, and absorption spectra, where energy is absorbed. 24:04 Energy Levels in Atoms The concept of the emission spectrum is explained through the observation of energy transitions, where the type of spectrum depends on whether energy is emitted or absorbed. The syllabus focuses specifically on emission spectra, neglecting absorption spectra, which can reveal the nature of elements when analyzed through a spectrometer. For instance, examining hydrogen light with a spectrometer clearly demonstrates the characteristics of its emission spectrum. 24:54 Emission and Absorption Spectra The differences between discrete and continuous spectra are crucial for understanding emission and absorption spectra in atomic physics. Emission spectra are discrete, occurring with specific wavelengths as electrons transition between energy levels, while absorption spectra are continuous, representing a range of wavelengths. Key concepts include the distinction in nature between these spectra as well as their implications for both academic examinations and practical engineering applications. 40:27 Quantum Mechanics Energy exists in discrete bundles, known as quanta, illustrating the principles of quantum physics. Electrons orbit around the nucleus in circular paths, as described by Neil, emphasizing the central role of centripetal force in their motion. Understanding these concepts is foundational for exploring the quantum realm. 41:18 Bundles of Energy In circular motion, a centripetal force is required, which is provided by the electrostatic force in the case of atoms, where protons are at the center and electrons orbiting outside. According to Coulomb's law, this electrostatic force can be expressed as F = k(q1q2)/r², highlighting the relationship between force and distance. Understanding these forces is crucial for grasping the structure of atoms. 42:09 Centripetal Force The discussion highlights the simplification of electrical terms by using symbols such as 'm' for electron mass and 'r' for radius, while emphasizing the importance of underlying principles like the electrostatic force represented by the equation F = k(q1q2)/r². The relations between electron and proton charges are outlined, with a focus on their magnitudes, leading to the formulation of the first equation concerning centripetal force in this context. 43:11 Electrostatic Force The goal is to generalize beyond hydrogen by considering elements like sodium, which has 11 protons and 11 electrons. To achieve this generalization, the equations will involve multiplying by 'z' to account for the varying number of protons and electrons, moving away from the limitations of specific cases such as hydrogen, which was primarily addressed by Bohr. 43:59 Generalization of Bohr's Model Bohr accepted the atomic model and focused on hydrogen's perspective in his analysis of spectra. He refuted Rutherford's claims that electrons would spiral into the nucleus due to energy loss, asserting instead that electrons do not move randomly in a way that would lead to such a collapse. 44:48 Atomic Model Focus Electrons revolve in specific orbits around the nucleus, not randomly at varying radii like 10 cm or 8 cm. In these specific orbits, electrons do not require energy to maintain their motion, as their energy levels are quantized. The radius of an electron's orbit can only take certain discrete values defined by its angular momentum, expressed mathematically as nh/2π. 45:43 Specific Orbits of Electrons Electrons can only occupy specific orbits where their angular momentum is quantized, which introduces the principles of quantum physics. This concept can be difficult to grasp, particularly when comparing it to classical physics; for example, quantum physics suggests that one can pass through walls, whereas classical physics denies this possibility. This highlights the fundamentally different nature of quantum reality. 46:35 Quantum Physics Introduction The discussion revolves around the energy levels of electrons in orbits, specifically how energy is required for an electron to transition from a higher to a lower energy level. For example, moving to the first energy level from the third consumes 20 Joules of energy, akin to the differences in living costs across cities. The concept elaborates on the varying energy expenditures based on the position in the energy levels. 47:34 Energy Levels and Transitions When an electron moves from a higher energy level to a lower one, it releases energy equal to the difference between the two levels, which can be illustrated by the example of a person achieving success and relocating for better opportunities. Conversely, when an electron gains energy and transitions to a higher level, it absorbs energy. The equation governing these energy transitions, while not explicitly given in textbooks, can be derived using the Rydberg constant. 48:24 Energy Release During Transitions The equation for energy differences relies on the higher energy level minus the lower energy level, which equals h times frequency. It's essential to present mathematical statements correctly in exams to ensure full credit; therefore, practicing derivations without subscripts can enhance confidence and understanding. Using a simplified notation, such as setting radius as 'r', avoids confusion often caused by more complex terms found in textbooks. 49:12 Mathematical Statements in Physics Substituting variables is a key strategy in mathematical problem-solving in physics. To find one quantity, eliminate another from the equations, such as removing velocity to solve for radius, or vice versa. This approach simplifies the process of isolating each variable for calculation. 50:04 Deriving Radius and Velocity Equations The derivation of the radius in an atomic model involves substituting velocity in terms of other constants and simplifying the equation to isolate the radius. The final expression for the radius, denoted as r = n² / z, emerges from the cancellation of constants and terms throughout the process. This leads to a conclusion that constants in physics should be replaced with a new constant for clarity, represented as a0, which signifies the base or principal radius.
I used to LIKE physics, You made me LOVE physics! And yes there's a huge difference between Liking and Loving Physics!!! Thank you sir RG sir ..a huge bow to you!
summary of topics 01:58:07 Types of Radioactive Decay Beta decay involves the emission of particles, primarily electrons, although the details about other particles remain insufficiently researched. Additionally, gamma decay results solely in the release of energy, indicating a different mechanism of decay. In heavy decay, helium nuclei may disappear, while energy loss can occur without significant mass change. 02:04:03 Beta Decay In beta decay, a proton splits into a neutron and an electron, with the electron being referred to as a positron due to its similar properties to that of an electron. The discussion includes the emission of energy through gamma rays, which are high-energy photons. Key concepts about these processes should be read and highlighted for better understanding. 02:04:59 Gamma Decay The discussion revolves around the characteristics of alpha, beta, and gamma particles, highlighting the essential data pertaining to them. A key focus is the derivation of the law of radioactivity, emphasizing the necessity to apply basic common sense in understanding the subject. An illustrative example is provided to explain the concept further by describing a scenario involving placing 50 apples in a balcony. 02:05:53 Decay Law Derivation The discussion uses the analogy of mice eating mangoes to explain the concept of nuclear decay rates, indicating that the more nuclei present, the greater the number of decays will occur, similar to how more mangoes attract more mice. It emphasizes that the decay rate is directly proportional to the number of nuclei present at any given time, thus illustrating the law of radioactive decay. Essentially, the analogy demonstrates that as the quantity of something increases, so does its consumption or decay. 02:08:55 Radioactive Decay Rate The discussion explains the concept of radioactive decay rates, emphasizing that the decay rate is proportional to the number of radioactive nuclei present at a given time. By applying logarithmic transformations, the final expression for the decay can be derived, leading to the well-known law of radioactive decay, which defines the activity as the number of disintegrations per unit time. This foundational principle is critical in understanding the behavior of radioactive materials in physics. 02:14:37 Activity Definition The discussion focuses on the definition of activity and its derivation using the formula related to decay, where the derivative reveals the association of constants that define activity over time. It emphasizes the importance of understanding the half-life concept from chemistry. The approach to summarizing this content underlines the need to identify specific terms and methods in nuclear context versus activity-based analysis. 02:16:33 Half-Life Concept The concept of half-life in chemistry is crucial for determining the decay of substances, defined as the time taken for half of the original nuclei to decay. The relationship between the initial quantity of nuclei and their remaining quantity after each half-life can be expressed mathematically. Specifically, the half-life is represented as t1/2, and involves using the natural logarithm to derive the time it takes for half of the substance to decay. 02:19:05 Half-Life Derivation The derivation of the half-life formula begins by examining the decay of nuclei over time, with time zero representing the initial state where all nuclei are intact. As time approaches infinity, no nuclei survive, leading to a calculation of average life by integrating decay rates and dividing by the original number of nuclei. Ultimately, the average lifetime of a radioactive species is determined to be inversely proportional to the decay constant. 02:24:58 Nuclear Fusion and Fission Nuclear fission involves the process where a heavy nucleus splits into two lighter nuclei, releasing energy in the process. Conversely, nuclear fusion is the merging of two nuclei to form a heavier nucleus, also releasing energy. Understanding these processes is crucial, and while examples are provided, they are primarily for memorization rather than detailed explanation. 02:26:59 Nuclear Stability The 15th chapter on the Structure of Atoms and Nuclei is concluded with expectations of sharing notes and resources through provided website links with friends and college mates.
summary of topics 54:34 Final Expressions for Radius The value of a0 is established as 0.53 Å, leading to the relationship where the radius (r) is directly proportional to the square of the principal quantum number (n). For hydrogen atoms, r then relates to n/z, allowing the velocity formula derivation, which ultimately shows that velocity is directly proportional to z/n. Key canceling processes and the implications of constants are noted, reinforcing that these relationships are foundational for atomic physics. 59:33 Velocity Proportionality The discussion emphasizes the significance of time factors in formulas related to velocity and radius, highlighting how these relationships dominate calculations. It transitions to the last topic on the energy of electrons, detailing the derivation's final answer. A recommendation is made to take a screenshot for reference. 01:00:25 Total Energy of Electron The content highlights discrepancies in previously distributed textbooks, noting that while newer editions have corrections, older texts contain incorrect answers. It emphasizes a straightforward presentation of formulas, with derivations simplified into a single step. The speaker includes a discussion on total energy, which is the sum of kinetic and potential energy, and expresses the kinetic energy formula as 1/2 mv², engaging the audience for further interaction. 01:01:15 Kinetic and Potential Energy The expression for velocity has been established, and it will be substituted to derive the final expression for kinetic energy, which involves mass and squared terms. In the electrostatics chapter, potential energy is derived from the work done expression, specifically equating it to k * (q^2)/r, where energy is associated with work done per unit charge. It's important to note that potential energy is always represented as negative, reflecting the nature of gravity and electrostatics. 01:03:44 Negative Potential Energy Potential energy is negative for bound states, as both electrons and protons are constrained by the nucleus, similar to how a person cannot escape Earth's gravity. The expression for potential energy, derived and generalized for hydrogen atoms, involves a negative factor proportional to the square of the atomic number (z) and inversely proportional to the distance (r). The total energy can be calculated using this potential energy expression along with kinetic energy, leading to findings on the relationship between energy and quantum states. 01:11:14 Ionization Energy Concept The concept of ionization energy is illustrated using a chocolate shake analogy, emphasizing that if a friend drinks a shake at a shop, the shopkeeper will inform you of this, paralleling the energy transition in atomic orbitals. When an electron jumps from a higher to a lower orbital, energy is released, which reflects the energy difference described by the Rydberg formula. This shift exemplifies how energy dynamics function within atomic structures. 01:12:07 Rydberg Formula Derivation The derivation of the Rydberg formula involves manipulating expressions of energy related to electron orbits, where various constants, including electron mass and the fundamental constants, are considered. By substituting the expressions into a formula and recognizing common terms, the final equation emerges, which relates the wavelengths of light to the Rydberg constant. This highlights the connections between quantum mechanics and atomic structure, culminating in an expression for energy transitions in hydrogen-like atoms. 01:15:06 Energy Differences in Orbits The derivation of the famous Rydberg formula for hydrogen involves recognizing that hydrogen has a value of z equal to one. For any other atom, the value of z can be multiplied accordingly to find equivalent results. The chapter concludes with several important derivations, including the total energy of electrons, radius and velocity, and highlights essential points for exam preparation. 01:17:40 De Broglie's Hypothesis In exploring wave behavior, it is noted that the circumference of a circle (2πr) encompasses multiple wavelengths. The author reflects on personal research in quantum physics, revealing that electrons are fundamentally represented by stationary waves, as they remain bound and do not exist freely. 01:17:40 De Broglie Hypothesis Waves behave in a circular manner and display various wavelength covers during this interaction. Research indicates that electrons represent stationary waves due to their bound nature, and the connection is supported by De Broglie's formulation, which relates angular momentum to integral multiples of h/2π. The discussion transitions to the concept of atomic nuclei, highlighting protons as positively charged and neutrons as neutral particles, collectively forming the nucleus.
sir maximum students ne apke saare one shot dekh liye hai and we would be very thankful if u took a live session where u just give 🌟mind map🌟 of all chapters for like 45 minutes each. sir bohot help ho jayegi sirf itna kar do.
summary of topics 01:21:56 Atomic Number and Mass Number The atomic number of an atom is defined as the number of protons it contains, and in a stable atom, the number of protons equals the number of electrons. The mass number, denoted by A, is the total number of protons and neutrons in the nucleus, where neutrons are represented by N. Isotopes are variations of elements that have the same number of protons but different numbers of neutrons, with examples primarily focusing on hydrogen and its isotopes. 01:25:13 Isotopes and Isobars Isotopes and isobars both have the same mass number but differ in their number of protons. Isotopes maintain the same number of protons while varying in neutrons, whereas isobars have the same mass number with differing proton counts. Understanding these differences can be aided by recalling that in isotopes, the lower part remains constant, while in isobars, the upper part varies. 01:28:29 Atomic Mass Unit The content discusses the concept of the Atomic Mass Unit (AMU), emphasizing its practical usage in 11th and 12th standard physics. It explains the definition of 1 AMU as 1/12 of the mass of a neutral carbon atom with atomic number 12, highlighting its relevance in simplifying calculations compared to using kilograms. Furthermore, it touches upon the relationship between atomic size and electron orbits, as well as the forces acting within an atom, positing that the nuclear force is the strongest among them. 01:36:49 Nuclear Forces Nuclear force, despite its short range, is the strongest force, surpassing electrostatic forces, which act on positive charges that repel each other within atomic nuclei. The stability of the nucleus is attributed to the nuclear force, preventing protons from repelling each other, unlike the gravitational force which, despite its infinite range, is the weakest among all forces. Additionally, the concept of binding energy is introduced, illustrating how electrons are bound to the nucleus rather than being free. 01:40:54 Binding Energy Binding energy, quantified at 13.4 electron volts, is essential as it keeps atomic particles bound within the nucleus. In attempting to form a nucleus, energy is released from the mass of protons and neutrons combined; however, the actual measured mass of the nucleus is less than the expected total from its constituents due to mass defect, which reflects energy that has been converted and released. This phenomenon illustrates the interplay between mass and energy as described by Einstein's relation E=mc². 01:46:20 Mass Defect The discussion revolves around the calculation of mass defect in nuclear physics, specifically deriving it from the mass of nucleons comprising the nucleus. By determining the mass of the nucleus and subtracting the contributions of the protons and neutrons, it is found that the mass defect is 0.2 kg. This calculation leads to the formulation of binding energy, which is expressed in terms of mass and the speed of light squared, allowing for a deeper understanding of the energy relationships in atomic structures. 01:48:04 Mass Effect and Defect To formulate the generalized equation, the mass of the electron and the total mass of all electrons in an atom are added and subtracted. By factoring out z, the equation simplifies to the sum of the mass of a proton and the mass of an electron, specifically in a hydrogen atom, which allows for the representation of hydrogen's mass alongside its number of electrons. Thus, z represents the number of particles, and m signifies the mass of a single particle. 01:48:53 Generalized Equation for Mass The discussion centers on the mass of a nucleus, denoted as 'm', and how adding the mass of electrons yields the total atomic mass. This process essentially reflects the fundamental equation used in determining mass numbers, which are crucial for solving problems related to nuclear physics and binding energy concepts. 01:49:53 Binding Energy Expression Binding energy can be understood in two ways: the energy required to free a nucleon from the nucleus, which is positive, and the energy associated with the nucleon being bound, which is negative. For example, if the binding energy is -13.6 electron volts, it indicates that +13.6 electron volts is needed to release the nucleon, allowing comparisons regarding the binding capacities of different nucleons. 01:50:46 Binding Energy Concept Higher binding energy indicates greater stability of the nucleus, as stronger elements require more energy to be removed. Conversely, elements with lower binding energy are less stable. The relationship between mass, attraction, and binding energy is crucial, with an observed trend showing increased binding energy correlating with atomic mass. 01:51:49 Stability and Binding Energy The graph of elemental activity in chemical reactions appears fluctuating due to the presence of various elements, particularly the hyper-active ones, while noble gases like helium remain inactive. Among the elements, iron demonstrates the highest value in the graph before it declines further. This fluctuation essentially reflects the reactivity levels of these elements. 01:52:39 Graph of Binding Energy The atomic number of iron is 56, indicating that as the elements increase, the number of protons also rises. While nuclear force is the strongest force, its range is limited, which becomes significant as the nucleus enlarges, leading to increased mass and radius that allow electrostatic forces to dominate. 01:53:34 Nuclear Force and Stability As nuclear forces progress, subsequent nuclei become less stable due to their increasing weights. This fundamental concept of binding energy leads to discussions on radioactivity, where a decrease in the number of protons indicates a well-managed and settled system, although issues may arise over time. 01:54:31 Radioactivity Introduction As protons increase in number within an atom's nucleus, a point is reached where the nuclear force can no longer contain them, leading to instability. This situation can be likened to overindulging at a feast, where excessive amounts create a state of imbalance. Ultimately, when the pressure becomes too great, the nucleus may experience a form of 'explosion' or instability. 01:55:22 Nuclear Instability Dieting often leads to overindulgence on the last day before starting a diet, resulting in excessive eating that can trigger vomiting. There are three types of vomiting: the first expels both food and liquid consumed, the second mainly releases fluids due to trapped gas, and the third resembles sour burps without actual vomiting. The analogy is drawn with atomic behavior, where the first type of vomiting relates to the release of a heavy helium nucleus, the second involves the emission of a single electron, illustrating the varying impacts on the body. 01:58:07 Types of Radioactive Decay Beta decay involves the emission of particles, primarily electrons, although the details about other particles remain insufficiently researched. Additionally, gamma decay results solely in the release of energy, indicating a different mechanism of decay. In heavy decay, helium nuclei may disappear, while energy loss can occur without significant mass change.
Sir me bata nahi sakta ye videos in last ke dino me kitne help full ho rahe hai becoz saal bhar jitna padha hai ye possible nahi tha hamare liye 3 din me complete karna but apne possible kar dikhaya thankyou so much sir hats off for your efforts ❤❤❤❤
Kisne notice kiya Soothe soothe mat padho, pith mai dard hoga Uska reply check mt karo baar baar, nhi degi What an interesting way to keep students engage ✨
Very helpful .. I completed all the chapters from this playlist being a jee aspirant it helps me to revise in FastTrack mode ... thanks for saving my h time sir means a lot🙌🙌
sir im a student always with curious WH ques and most teachers ask to ratify things, so the best part about ur lectures are the weird funny examples which make things so much easier to visualise & understand🙇🏻♀️
Thankyou so much sir ❤Textbook really confused me with incomplete explanation, everytime i read something and i don't understand i know you'll always have an explanation to it ❤
Thank you so much for making these one shot videos sir I used find physics difficult but now every thing makes sense every equation and every chp just because of you thank you sir!
summary of topics 00:51
Structure of Atoms
The session begins by emphasizing the importance of understanding history to grasp the structure of matter. It highlights Dalton's theory, which presented three key points, notably that matter is composed of indivisible elements, referred to today as atoms. Specifically, it denotes that each element, like sodium with 11 atoms, is defined by its unique atomic configuration.
01:43
History of Atomic Theory
Sodium atoms in different cities possess the same structure, with each retaining 11 electrons. When sodium combines with chlorine, it forms sodium chloride, resulting in a new substance. Regarding Thomson's theory, it is considered 50% successful due to its contributions and limitations in atomic discovery.
02:49
Dalton's Theory
थॉमसन ने कैथोड रे एक्सपेरिमेंट के माध्यम से इलेक्ट्रॉनों का पता लगाया, जो एक सफल खोज थी। उसने प्लम पुडिंग मॉडल पेश किया, जिसमें उसने इसे वाटरमेलन की संरचना के समान रखा, जहाँ आतम का पूरा हिस्सा सकारात्मक चार्ज के समान है। इस मॉडल ने परमाणु की संरचना को एक नया दृष्टिकोण प्रदान किया।
03:45
Thomson's Theory
The watermelon serves as an analogy for atomic structure, illustrating that the body of the watermelon represents the positively charged atom, while the seeds symbolize negatively charged electrons. According to J.J. Thomson, the atom is primarily positive with negatively charged electrons embedded within it, yet the overall atom is electrically neutral. This clarification challenges the notion of a purely positively charged atom.
04:36
Plum Pudding Model
Atoms are electrically neutral, containing an equal number of positively charged protons and negatively charged electrons. The electrons orbit the nucleus, and the failure of the Plum Pudding Model is demonstrated through experiments like the Cathode Ray Experiment, which indicated the existence of electrons as negatively charged particles attracted to positive charges. Rutherford's Gold Foil Experiment further challenged the Plum Pudding Model, leading to the understanding of the atom's structure.
08:39
Rutherford's Gold Foil Experiment
Rutherford's gold foil experiment demonstrated that while most alpha particles passed through gold foil without scattering, a small fraction were deflected, leading to the conclusion that atoms are mostly empty space with a dense nucleus at the center. This realization highlighted that 99.9% of the atom's volume is unoccupied, underscoring the significant difference between the size of the nucleus and the atom itself. Additionally, the experiment raised questions about the stability of the atom and the behavior of electrons around the nucleus.
20:18
Atomic Spectra
Atomic spectra arise when electrons transition between energy levels within atoms, releasing or absorbing energy in the process. This was illustrated in a memorable class trip to Gajanan Market, where students used a spectrometer to observe various light sources, leading to a humorous incident with shopkeepers who thought their crowd was suspicious. There are two types of spectra: emission spectra, where energy is released, and absorption spectra, where energy is absorbed.
24:04
Energy Levels in Atoms
The concept of the emission spectrum is explained through the observation of energy transitions, where the type of spectrum depends on whether energy is emitted or absorbed. The syllabus focuses specifically on emission spectra, neglecting absorption spectra, which can reveal the nature of elements when analyzed through a spectrometer. For instance, examining hydrogen light with a spectrometer clearly demonstrates the characteristics of its emission spectrum.
24:54
Emission and Absorption Spectra
The differences between discrete and continuous spectra are crucial for understanding emission and absorption spectra in atomic physics. Emission spectra are discrete, occurring with specific wavelengths as electrons transition between energy levels, while absorption spectra are continuous, representing a range of wavelengths. Key concepts include the distinction in nature between these spectra as well as their implications for both academic examinations and practical engineering applications.
40:27
Quantum Mechanics
Energy exists in discrete bundles, known as quanta, illustrating the principles of quantum physics. Electrons orbit around the nucleus in circular paths, as described by Neil, emphasizing the central role of centripetal force in their motion. Understanding these concepts is foundational for exploring the quantum realm.
41:18
Bundles of Energy
In circular motion, a centripetal force is required, which is provided by the electrostatic force in the case of atoms, where protons are at the center and electrons orbiting outside. According to Coulomb's law, this electrostatic force can be expressed as F = k(q1q2)/r², highlighting the relationship between force and distance. Understanding these forces is crucial for grasping the structure of atoms.
42:09
Centripetal Force
The discussion highlights the simplification of electrical terms by using symbols such as 'm' for electron mass and 'r' for radius, while emphasizing the importance of underlying principles like the electrostatic force represented by the equation F = k(q1q2)/r². The relations between electron and proton charges are outlined, with a focus on their magnitudes, leading to the formulation of the first equation concerning centripetal force in this context.
43:11
Electrostatic Force
The goal is to generalize beyond hydrogen by considering elements like sodium, which has 11 protons and 11 electrons. To achieve this generalization, the equations will involve multiplying by 'z' to account for the varying number of protons and electrons, moving away from the limitations of specific cases such as hydrogen, which was primarily addressed by Bohr.
43:59
Generalization of Bohr's Model
Bohr accepted the atomic model and focused on hydrogen's perspective in his analysis of spectra. He refuted Rutherford's claims that electrons would spiral into the nucleus due to energy loss, asserting instead that electrons do not move randomly in a way that would lead to such a collapse.
44:48
Atomic Model Focus
Electrons revolve in specific orbits around the nucleus, not randomly at varying radii like 10 cm or 8 cm. In these specific orbits, electrons do not require energy to maintain their motion, as their energy levels are quantized. The radius of an electron's orbit can only take certain discrete values defined by its angular momentum, expressed mathematically as nh/2π.
45:43
Specific Orbits of Electrons
Electrons can only occupy specific orbits where their angular momentum is quantized, which introduces the principles of quantum physics. This concept can be difficult to grasp, particularly when comparing it to classical physics; for example, quantum physics suggests that one can pass through walls, whereas classical physics denies this possibility. This highlights the fundamentally different nature of quantum reality.
46:35
Quantum Physics Introduction
The discussion revolves around the energy levels of electrons in orbits, specifically how energy is required for an electron to transition from a higher to a lower energy level. For example, moving to the first energy level from the third consumes 20 Joules of energy, akin to the differences in living costs across cities. The concept elaborates on the varying energy expenditures based on the position in the energy levels.
47:34
Energy Levels and Transitions
When an electron moves from a higher energy level to a lower one, it releases energy equal to the difference between the two levels, which can be illustrated by the example of a person achieving success and relocating for better opportunities. Conversely, when an electron gains energy and transitions to a higher level, it absorbs energy. The equation governing these energy transitions, while not explicitly given in textbooks, can be derived using the Rydberg constant.
48:24
Energy Release During Transitions
The equation for energy differences relies on the higher energy level minus the lower energy level, which equals h times frequency. It's essential to present mathematical statements correctly in exams to ensure full credit; therefore, practicing derivations without subscripts can enhance confidence and understanding. Using a simplified notation, such as setting radius as 'r', avoids confusion often caused by more complex terms found in textbooks.
49:12
Mathematical Statements in Physics
Substituting variables is a key strategy in mathematical problem-solving in physics. To find one quantity, eliminate another from the equations, such as removing velocity to solve for radius, or vice versa. This approach simplifies the process of isolating each variable for calculation.
50:04
Deriving Radius and Velocity Equations
The derivation of the radius in an atomic model involves substituting velocity in terms of other constants and simplifying the equation to isolate the radius. The final expression for the radius, denoted as r = n² / z, emerges from the cancellation of constants and terms throughout the process. This leads to a conclusion that constants in physics should be replaced with a new constant for clarity, represented as a0, which signifies the base or principal radius.
Which ai did you use?
I was sure that you won't betray us proud to be your student 😭🤧
Betray for what??
Car
Sir plz upload one shot of semiconductor devices also .plz upload it today..THANKS FOR UR EFFORTS 👍👍
Ruk Jaa bhai unki sleep cycle kharab ho gayi hai 😢
Vo kaha abhi bejva denge video
2:12:42 Ye DINESH sir ne padhya hai ki PC ME log ke base me e aur MATHS ME log ke base me 10 hota hai
Nhi ln ke base me e hota hai
NO, PC mai Log to base 10 and Maths mai log to base e hota hai
Jo log table me log nikalate hai wo log to base 10 hota hai
1:23:41 subtitles are damn creative
motivation 😂😂
1:24:30 that sote sote mat padho Peet m dard hoga was exactly meant for me 😂😂😂
I used to LIKE physics,
You made me LOVE physics!
And yes there's a huge difference between Liking and Loving Physics!!!
Thank you sir
RG sir ..a huge bow to you!
1:02:25 potential energy 😅
😂
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summary of topics 01:58:07
Types of Radioactive Decay
Beta decay involves the emission of particles, primarily electrons, although the details about other particles remain insufficiently researched. Additionally, gamma decay results solely in the release of energy, indicating a different mechanism of decay. In heavy decay, helium nuclei may disappear, while energy loss can occur without significant mass change.
02:04:03
Beta Decay
In beta decay, a proton splits into a neutron and an electron, with the electron being referred to as a positron due to its similar properties to that of an electron. The discussion includes the emission of energy through gamma rays, which are high-energy photons. Key concepts about these processes should be read and highlighted for better understanding.
02:04:59
Gamma Decay
The discussion revolves around the characteristics of alpha, beta, and gamma particles, highlighting the essential data pertaining to them. A key focus is the derivation of the law of radioactivity, emphasizing the necessity to apply basic common sense in understanding the subject. An illustrative example is provided to explain the concept further by describing a scenario involving placing 50 apples in a balcony.
02:05:53
Decay Law Derivation
The discussion uses the analogy of mice eating mangoes to explain the concept of nuclear decay rates, indicating that the more nuclei present, the greater the number of decays will occur, similar to how more mangoes attract more mice. It emphasizes that the decay rate is directly proportional to the number of nuclei present at any given time, thus illustrating the law of radioactive decay. Essentially, the analogy demonstrates that as the quantity of something increases, so does its consumption or decay.
02:08:55
Radioactive Decay Rate
The discussion explains the concept of radioactive decay rates, emphasizing that the decay rate is proportional to the number of radioactive nuclei present at a given time. By applying logarithmic transformations, the final expression for the decay can be derived, leading to the well-known law of radioactive decay, which defines the activity as the number of disintegrations per unit time. This foundational principle is critical in understanding the behavior of radioactive materials in physics.
02:14:37
Activity Definition
The discussion focuses on the definition of activity and its derivation using the formula related to decay, where the derivative reveals the association of constants that define activity over time. It emphasizes the importance of understanding the half-life concept from chemistry. The approach to summarizing this content underlines the need to identify specific terms and methods in nuclear context versus activity-based analysis.
02:16:33
Half-Life Concept
The concept of half-life in chemistry is crucial for determining the decay of substances, defined as the time taken for half of the original nuclei to decay. The relationship between the initial quantity of nuclei and their remaining quantity after each half-life can be expressed mathematically. Specifically, the half-life is represented as t1/2, and involves using the natural logarithm to derive the time it takes for half of the substance to decay.
02:19:05
Half-Life Derivation
The derivation of the half-life formula begins by examining the decay of nuclei over time, with time zero representing the initial state where all nuclei are intact. As time approaches infinity, no nuclei survive, leading to a calculation of average life by integrating decay rates and dividing by the original number of nuclei. Ultimately, the average lifetime of a radioactive species is determined to be inversely proportional to the decay constant.
02:24:58
Nuclear Fusion and Fission
Nuclear fission involves the process where a heavy nucleus splits into two lighter nuclei, releasing energy in the process. Conversely, nuclear fusion is the merging of two nuclei to form a heavier nucleus, also releasing energy. Understanding these processes is crucial, and while examples are provided, they are primarily for memorization rather than detailed explanation.
02:26:59
Nuclear Stability
The 15th chapter on the Structure of Atoms and Nuclei is concluded with expectations of sharing notes and resources through provided website links with friends and college mates.
summary of topics 54:34
Final Expressions for Radius
The value of a0 is established as 0.53 Å, leading to the relationship where the radius (r) is directly proportional to the square of the principal quantum number (n). For hydrogen atoms, r then relates to n/z, allowing the velocity formula derivation, which ultimately shows that velocity is directly proportional to z/n. Key canceling processes and the implications of constants are noted, reinforcing that these relationships are foundational for atomic physics.
59:33
Velocity Proportionality
The discussion emphasizes the significance of time factors in formulas related to velocity and radius, highlighting how these relationships dominate calculations. It transitions to the last topic on the energy of electrons, detailing the derivation's final answer. A recommendation is made to take a screenshot for reference.
01:00:25
Total Energy of Electron
The content highlights discrepancies in previously distributed textbooks, noting that while newer editions have corrections, older texts contain incorrect answers. It emphasizes a straightforward presentation of formulas, with derivations simplified into a single step. The speaker includes a discussion on total energy, which is the sum of kinetic and potential energy, and expresses the kinetic energy formula as 1/2 mv², engaging the audience for further interaction.
01:01:15
Kinetic and Potential Energy
The expression for velocity has been established, and it will be substituted to derive the final expression for kinetic energy, which involves mass and squared terms. In the electrostatics chapter, potential energy is derived from the work done expression, specifically equating it to k * (q^2)/r, where energy is associated with work done per unit charge. It's important to note that potential energy is always represented as negative, reflecting the nature of gravity and electrostatics.
01:03:44
Negative Potential Energy
Potential energy is negative for bound states, as both electrons and protons are constrained by the nucleus, similar to how a person cannot escape Earth's gravity. The expression for potential energy, derived and generalized for hydrogen atoms, involves a negative factor proportional to the square of the atomic number (z) and inversely proportional to the distance (r). The total energy can be calculated using this potential energy expression along with kinetic energy, leading to findings on the relationship between energy and quantum states.
01:11:14
Ionization Energy Concept
The concept of ionization energy is illustrated using a chocolate shake analogy, emphasizing that if a friend drinks a shake at a shop, the shopkeeper will inform you of this, paralleling the energy transition in atomic orbitals. When an electron jumps from a higher to a lower orbital, energy is released, which reflects the energy difference described by the Rydberg formula. This shift exemplifies how energy dynamics function within atomic structures.
01:12:07
Rydberg Formula Derivation
The derivation of the Rydberg formula involves manipulating expressions of energy related to electron orbits, where various constants, including electron mass and the fundamental constants, are considered. By substituting the expressions into a formula and recognizing common terms, the final equation emerges, which relates the wavelengths of light to the Rydberg constant. This highlights the connections between quantum mechanics and atomic structure, culminating in an expression for energy transitions in hydrogen-like atoms.
01:15:06
Energy Differences in Orbits
The derivation of the famous Rydberg formula for hydrogen involves recognizing that hydrogen has a value of z equal to one. For any other atom, the value of z can be multiplied accordingly to find equivalent results. The chapter concludes with several important derivations, including the total energy of electrons, radius and velocity, and highlights essential points for exam preparation.
01:17:40
De Broglie's Hypothesis
In exploring wave behavior, it is noted that the circumference of a circle (2πr) encompasses multiple wavelengths. The author reflects on personal research in quantum physics, revealing that electrons are fundamentally represented by stationary waves, as they remain bound and do not exist freely.
01:17:40
De Broglie Hypothesis
Waves behave in a circular manner and display various wavelength covers during this interaction. Research indicates that electrons represent stationary waves due to their bound nature, and the connection is supported by De Broglie's formulation, which relates angular momentum to integral multiples of h/2π. The discussion transitions to the concept of atomic nuclei, highlighting protons as positively charged and neutrons as neutral particles, collectively forming the nucleus.
1:35:42 strongest force is nuclear force
Amazing detailed lecture sir thankyou so muchh!❤
1:35:37 NUCLEAR FORCE is the strongest.
BINDING enegry is -13.6ev na sir
sir eats 100 other physics techers in breakfast
Finally !!!!🎉 DON IS BACK 🔙❤
01:23:39 atomic nuclei
Jiska mujhe the intezaar jiske liye Dil tha bekrarr woh ghadi AAA gayi aagayi 😂😂 thank you soo. Much sir ❤❤❤❤
Sir I want it's pdf notes and I also want to write on it.. or take printout for revision but I'm not able to do than in your app.. plss help.. 😢
Thank You Rahul sir 🙏🏻
Waiting for a week for this wonderful lecture.
1:02:25 sir yeah kya tha😅
😂
😂😂
Paad😂
😂😂😂
Saliva andar lene ki awayz thi vo
1:35:40 Nuclear force: shortest range, strongest force
Thank you so much Sir 🚩🚩🚩🚩🚩
1:56:32 -_- example dena ka tareeka thoda kazual hai
sir semiconductor bhi daldo aaj he hosake to🙏
1:35:28 C) Nuclear Force
Edit: But now understand the reason behind this.😊Thank you sir❤
1:52:49 sir yaha toda mistake hai Fe atomic no 26 hota hai
sir as u said that u where blessed with good physics teacher ..... u continued that chain.
love the way of teaching and examples💛💛
Thank you so much sir very amazing and helpful lecture world best teacher physics 🎉🎉🎉❤❤❤❤❤❤
sir maximum students ne apke saare one shot dekh liye hai and we would be very thankful if u took a live session where u just give 🌟mind map🌟 of all chapters for like 45 minutes each. sir bohot help ho jayegi sirf itna kar do.
VERY VERY THANK YOU SIR❤❤🎉 mai kab se wait kar raha tha is Lecture ka
Rg sir back with a banger ❤❤
Very much awaited video
Thank you sir to save us at last moment ❤😊
apsolan gayab kaise hua 1:08:19
Gayab nahi hua dekho andar multiply hoke vo apsalon square bangaya and then denominator common leke subtract kia he 😮
Epsilon hai wo
@@Preditz999 whatever
summary of topics 01:21:56
Atomic Number and Mass Number
The atomic number of an atom is defined as the number of protons it contains, and in a stable atom, the number of protons equals the number of electrons. The mass number, denoted by A, is the total number of protons and neutrons in the nucleus, where neutrons are represented by N. Isotopes are variations of elements that have the same number of protons but different numbers of neutrons, with examples primarily focusing on hydrogen and its isotopes.
01:25:13
Isotopes and Isobars
Isotopes and isobars both have the same mass number but differ in their number of protons. Isotopes maintain the same number of protons while varying in neutrons, whereas isobars have the same mass number with differing proton counts. Understanding these differences can be aided by recalling that in isotopes, the lower part remains constant, while in isobars, the upper part varies.
01:28:29
Atomic Mass Unit
The content discusses the concept of the Atomic Mass Unit (AMU), emphasizing its practical usage in 11th and 12th standard physics. It explains the definition of 1 AMU as 1/12 of the mass of a neutral carbon atom with atomic number 12, highlighting its relevance in simplifying calculations compared to using kilograms. Furthermore, it touches upon the relationship between atomic size and electron orbits, as well as the forces acting within an atom, positing that the nuclear force is the strongest among them.
01:36:49
Nuclear Forces
Nuclear force, despite its short range, is the strongest force, surpassing electrostatic forces, which act on positive charges that repel each other within atomic nuclei. The stability of the nucleus is attributed to the nuclear force, preventing protons from repelling each other, unlike the gravitational force which, despite its infinite range, is the weakest among all forces. Additionally, the concept of binding energy is introduced, illustrating how electrons are bound to the nucleus rather than being free.
01:40:54
Binding Energy
Binding energy, quantified at 13.4 electron volts, is essential as it keeps atomic particles bound within the nucleus. In attempting to form a nucleus, energy is released from the mass of protons and neutrons combined; however, the actual measured mass of the nucleus is less than the expected total from its constituents due to mass defect, which reflects energy that has been converted and released. This phenomenon illustrates the interplay between mass and energy as described by Einstein's relation E=mc².
01:46:20
Mass Defect
The discussion revolves around the calculation of mass defect in nuclear physics, specifically deriving it from the mass of nucleons comprising the nucleus. By determining the mass of the nucleus and subtracting the contributions of the protons and neutrons, it is found that the mass defect is 0.2 kg. This calculation leads to the formulation of binding energy, which is expressed in terms of mass and the speed of light squared, allowing for a deeper understanding of the energy relationships in atomic structures.
01:48:04
Mass Effect and Defect
To formulate the generalized equation, the mass of the electron and the total mass of all electrons in an atom are added and subtracted. By factoring out z, the equation simplifies to the sum of the mass of a proton and the mass of an electron, specifically in a hydrogen atom, which allows for the representation of hydrogen's mass alongside its number of electrons. Thus, z represents the number of particles, and m signifies the mass of a single particle.
01:48:53
Generalized Equation for Mass
The discussion centers on the mass of a nucleus, denoted as 'm', and how adding the mass of electrons yields the total atomic mass. This process essentially reflects the fundamental equation used in determining mass numbers, which are crucial for solving problems related to nuclear physics and binding energy concepts.
01:49:53
Binding Energy Expression
Binding energy can be understood in two ways: the energy required to free a nucleon from the nucleus, which is positive, and the energy associated with the nucleon being bound, which is negative. For example, if the binding energy is -13.6 electron volts, it indicates that +13.6 electron volts is needed to release the nucleon, allowing comparisons regarding the binding capacities of different nucleons.
01:50:46
Binding Energy Concept
Higher binding energy indicates greater stability of the nucleus, as stronger elements require more energy to be removed. Conversely, elements with lower binding energy are less stable. The relationship between mass, attraction, and binding energy is crucial, with an observed trend showing increased binding energy correlating with atomic mass.
01:51:49
Stability and Binding Energy
The graph of elemental activity in chemical reactions appears fluctuating due to the presence of various elements, particularly the hyper-active ones, while noble gases like helium remain inactive. Among the elements, iron demonstrates the highest value in the graph before it declines further. This fluctuation essentially reflects the reactivity levels of these elements.
01:52:39
Graph of Binding Energy
The atomic number of iron is 56, indicating that as the elements increase, the number of protons also rises. While nuclear force is the strongest force, its range is limited, which becomes significant as the nucleus enlarges, leading to increased mass and radius that allow electrostatic forces to dominate.
01:53:34
Nuclear Force and Stability
As nuclear forces progress, subsequent nuclei become less stable due to their increasing weights. This fundamental concept of binding energy leads to discussions on radioactivity, where a decrease in the number of protons indicates a well-managed and settled system, although issues may arise over time.
01:54:31
Radioactivity Introduction
As protons increase in number within an atom's nucleus, a point is reached where the nuclear force can no longer contain them, leading to instability. This situation can be likened to overindulging at a feast, where excessive amounts create a state of imbalance. Ultimately, when the pressure becomes too great, the nucleus may experience a form of 'explosion' or instability.
01:55:22
Nuclear Instability
Dieting often leads to overindulgence on the last day before starting a diet, resulting in excessive eating that can trigger vomiting. There are three types of vomiting: the first expels both food and liquid consumed, the second mainly releases fluids due to trapped gas, and the third resembles sour burps without actual vomiting. The analogy is drawn with atomic behavior, where the first type of vomiting relates to the release of a heavy helium nucleus, the second involves the emission of a single electron, illustrating the varying impacts on the body.
01:58:07
Types of Radioactive Decay
Beta decay involves the emission of particles, primarily electrons, although the details about other particles remain insufficiently researched. Additionally, gamma decay results solely in the release of energy, indicating a different mechanism of decay. In heavy decay, helium nuclei may disappear, while energy loss can occur without significant mass change.
Thankyou sir you are best in the world ❤❤❤❤
Hats off SIR for making 2.5 hrs oneshot also yall take 5 hrs to make it short , understanding and with less interrruptance .
1:35:39 sir yaha pe nuclear force sabse strong force hai
1:35:43 *nuclear force* is the strongest force ✅♥️🔥🔥🔥🔥
Yahhhhh 🔥🔥🔥🔥🔥🔥🔥
Are you dropper
Thanks sir. Can u please upload Semiconductor devices
1:35:45 Nuclear>Weak>electrostatic>gravitational
hag diya 💀
Sir me bata nahi sakta ye videos in last ke dino me kitne help full ho rahe hai becoz saal bhar jitna padha hai ye possible nahi tha hamare liye 3 din me complete karna but apne possible kar dikhaya thankyou so much sir hats off for your efforts ❤❤❤❤
Thank you so much for everything sir
Sir aap ulhasnagar mai kaha rehte ho ? Or konse class jate the?
Thank you so much sir,helped me understand the chapter from scrap,the way of teaching was very comfortable and easy 🙏🏼🙏🏼🙏🏼
🙏❤️ Keep Learning
Structure of atoms and Nuclei - One Shot Maharashtra Board Class 12th Physics RG lectures Revision
Day 7: asking Rg sir to comback on YT😢
❤❤❤sir you are such a lovely person or teacher that I want for my hole life
Kisne notice kiya
Soothe soothe mat padho, pith mai dard hoga
Uska reply check mt karo baar baar, nhi degi
What an interesting way to keep students engage ✨
1:35:41 nuclear force is the strongest force
1:35:57 a) Gravitational Force 🤔
chalo abse sikhgaya ( nuclear force is the strongest force )
Very helpful ..
I completed all the chapters from this playlist being a jee aspirant it helps me to revise in FastTrack mode ... thanks for saving my h time sir means a lot🙌🙌
1:35:45 c) Nuclear force
Mind blowing teaching ❤
Finally thanks sir very much just one more remaining 😢❤❤❤❤❤❤❤
1:36:01 answer. : nuclear force is the strongest force
1:35:42 gravitational
Now I know sir
20.25 a great teacher always respect s his teacher 😊😊
sir , i know as being science and space lover , the answer of 1:36:02 is nuclear force
1:57:18 examples nahi buluga
Thanks 🙏🏼 for this amazing lecture
1:35:48 nuclear force ❤❤
Yess🔥🔥 I am right 👍🏻 1:36:15 ❤
sir im a student always with curious WH ques and most teachers ask to ratify things, so the best part about ur lectures are the weird funny examples which make things so much easier to visualise & understand🙇🏻♀️
Thank you so much sir ..❤❤❤ (you are one of the biggest and beautiful part of my life )
Thanks bhaiya ❤❤❤❤❤
bhaiya aapaka 5 yrs old semiconductor ka video dekha hai.
@@tusharingle2690 ohh Thanks for constant support!
Bhaiya 5days ago aapkaa channel pata chala hai.
Thank you sir Literally ap dil se padte hoo❤🙌🫶
The truth lies at ..... 😅 13:17
Sir was born to teach physics ❤ , Thanks alot
Love you sir❤❤❤❤❤❤❤
Thank you sir for this amazing lecture ❤
0:00 haay
Thankyou so much sir ❤Textbook really confused me with incomplete explanation, everytime i read something and i don't understand i know you'll always have an explanation to it ❤
2:12:00 Smja 😅 muze jee aspirant hun na👍🏻🙃🙃
1:36:50 strong nuclear force
Nuclear force 1:35:40
Yesssss❤
Was waiting for this video..... Just thank you so much for making us feel that we will crack this exam ❤❤❤
FINALLY..WAS WAITING FOR THIS LECTURE!!!
Eagerly waited for this lecture ❤
Sir i want fastrack batch for physics Sir i have left jee my whole portion is completed help me sir pls 🙏🙏🙏
Hii crash course will come for MHTCET after boards
@ Thank you sir u are literally God gift 🫂❤️🥹❤️🔥❤️🩹🙏
1:35:42 nuclear forces
Sir semiconductors bhi upload kar do n aajj
Sir please upload semiconductor one shot video.
Waiting.... waiting... waiting
1:36:01 option (C)
thankyou so much sir 🤗
Very nice sir
Thanks😊
1:57:20 kya example hain ye toh marte vakt bhi yaad aajaye
Never did i think in my wildest dreams that I'll learn abt radioactive decay from ulti
😂😂😂
Sir , average life of radioactive species ka derivation exam me aane ke chances hai kya , i can skip the derivation of it?
Hi
1:18:24 sir ye patent karwalo
Bhaiya plz post neet related content
One of ur subscribers🎉🙏🙏🙏
sir 2025 ke bacho ke liye kuch dhamakedar layega sir🎉🎉 plz
Course me to dhamaka hi chalea hai bhai 🎉
i think nuclear force 2:27:23
Bohot accha session tha sir thank you 😊
This man doesn't teach phy but research phy which makes it more fun while other just say feeling lo ye feel Kara dete hai thanks sir ❤
Strong nucler force
Thank you so much for making these one shot videos sir
I used find physics difficult but now every thing makes sense every equation and every chp just because of you thank you sir!
1:35:54 nuclear forces are strongest in nature
😊
nuclear force
My answer - Nuclear force
With complete honesty my answer was correct.
Sir board exam me limitation of bohr's model pe sawal nahi ata kya? kyonki aapne wo part nahi liya