Alternating current, direct current & what is frequency? | Physics | Khan Academy
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- Опубликовано: 3 окт 2024
- Current that keeps changing is direction is called alternating current, (AC) whereas the one that never changes its direction is called direct current (DC). Power can be transmitted with low heating losses in the form of AC (not DC). The frequency of the AC in India is 50 Hz. This means the current changes it's direction 100 times per second.
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Created by Mahesh Shenoy
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In particle physics there is actually 'flavours for particles'
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Answers:
1.
DC - Direct current
AC - Alternating current
2. If the frequency is 50 Hz it means that there are 50 cycles in a current per second. Also, it means that the current changes it's direction 100 times a second (a cycle consists of the change of direction twice)
3. Sending a large amount of voltage through long distances is uneconomical thus a better way to reduce the cost us to send much lower voltage through the same distance and then increase the voltage through a transformation when it reaches its required location. Now, since the transformer only works if the current is alternating, the current reaching our homes is AC.
Feel free to correct my mistakes if any
Excellent video. Clear explanation 🙂
I believe another reason why high voltage / low current A.C is used in power lines is for cost reasons, so that thinner electrical cables (i.e. less copper) can be used.
Yeah, cause less energy is lost. There isn't as large a need to reduce resistance
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Transformer can be either step-up or step down. Especially in India, Transformers that we find near our home is step down. It converts high voltage ( usually 11 KV or 1100 Volts ) to low (415 volts). From the transformer three phase lines and one neutral is supplied to electric lines posts. Form that , one phase line and neutral line gives us normal 230 volts .
@Jo Hello
In ac current goes backwards and then foreword
When it goes backward or forward does it cover the whole circuit once
Or from some distance it come forward again
@@faxedits8The charges may not cover the whole circuit when it goes forward or backward.
When the charges flow from one point to another, they will continuously change their direction in a to and fro manner and reach the final destination .
If AC current “flows” in both directions, why is there a need to distinguish a live from a neutral wire?
The potential difference of the neutral is always kept very low(almost equal to zero).
Good question..
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Sir , one question that troubles a lot of people , if current alternates why do we distinguish the 2 cables (for a single phase ) as hot wire and neutral . if it alternates then shouldn't for the first half cycle the brown wire (L) to be the hot one and blue wire (N) to be the neutral and for the second half cycle the brown wire to be the neutral one and blue wire to be the hot one ?
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Sir in AC if current goes back and forth how will the destination be reached
Electrons go back and forth in the entire circuit...so the electrons also move inside the electrical components coz it's also a part of the circuit...i think so... I'm not sure...but i my teacher answered me that it's electrical energy which reaches the destination...
@@omm12459 you're right
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@@omm12459 both, it's the energy that's being transferred by making electrons swing back and forth
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Current come in 2 flavours 😁0:38
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can the magnitude of dc current change?
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Why the electrons flowing in A.C current moves back and forth, is it just to imagine or is it actually how it works? Well electrons bounce off of 1 atom to another, so does that mean it bounces and then bounces back to the same atom again? I can't understand why the electron are moving back and fourth in the A.C current.
Sir, I have a doubt.... if one electron is moving through the bulb for many times back and forth, then it should have lost its energy . But it hasn't. The bulb still glows brightly, 🤔
Ap Bada bada thanks bhaiya ,
What will be frequency of an A. C if its direction changes after every 0.01 second?
As direction changes for 0.01 sec, and also one cycle is of 2 directions, that implies 1 cycles takes a time of 0.02 secs... Frequency = 1/Time Period, here time period is 0.02 secs.... therefore, frequency = 1/(0.02) = 50 Hz... Hope this helps
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What will happen if the current is too high??
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Sir do the electrons complete one complete cycle throughout the circuit before changing their direction?
Totally depends on the frequency of alternation, the strength of the current, & the length of the wires
At high currents (high speed), low frequency (more time to alternate), and smaller circuits, electrons might complete multiple loops before changing direction.
Whereas in low currents, high frequency, and larger circuits, they might be just oscillating back and forth!
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Sir, if AC is the current driving behind tube lights and other devices, then why do fans rotate in one direction only, fans also receive AC, then fans should rotate in one direction and then in another direction, for a fan to rotate AC has to be converted in DC via rectifier, so my question is rectifier not used in powering tubelights ?
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When current flows through a bulb in our house, no short circuit. But if in the place of bulb a conductor is used, short circuit follows causing devastation. I do not think only consumption of electricity of the bulb can explain the thing.
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Sir I have dought on AC current ?
Current means flow of elections or charger particles ,that means current is moving ,ln AC current the charge particles does not move it just oscillat in the same place then how the current flow
Why can't we send low dc current and use the transformer to step up the current
Brilliant explanation, best video on this topic
In ac, if it moves back and forth, then how electron will reach destination
GOOD QUESTION
Same question bro
Wasim i found answer later bro
That electron will not move from source to destination.
Electricity is the movement of electrons
i.e electrons dont need to move from one place to another.
When the electrons just move front and back, the electricity is produced.
@@srinivasan3615 answer this question
Why fan not rotating or changing its direction in one cycle of wave ?
Why it is rotating in single direction? Bulb glows and offs
In that case fan rotation should alter
Aravindh Gunti fan converts electrical energy into kinetic energy
(Disclaimer: i m not a eee student 😂
I know just the basics)
really great video , just a seizure warning would have been nice on the flickering tubelight
Sir, please answer ,"why fuse is connected to live wire only"?
Rohit Nagwal
Fuse is connected with the phase wire(live wire) as the electric current flows from the live wire to neutral wire, hence in a case when current increase the live wire will get heated first as current flows through it first and then goes to the neutral wire.
So in cases of voltage fluctuations the flow electric current needs to be stopped hence the fuse is connected with the live wire.
@@anmolrajput9133 live wire doesn't carry all the current.
As current is a flow and hence it flows from live wire to neutral wire
Because if fuse is connected to neutral then in case of short circuit the fuse wire will break but still current with flow till electric appliance as it is still connected to live wire so, we may get electric shok if it is not connected to earthing.
What a handwriting