Geometric Optics: Crash Course Physics #38

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  • Опубликовано: 7 авг 2024
  • LIGHT! Let's talk about it today. Sunlight, moonlight, torchlight, and flashlight. They all come from different places, but they’re the very same thing: light! It’s what makes it possible for us to see the world around us, so it’s worth a close, hard look. For instance, how does light travel? When you flip that switch in the bathroom to brush your teeth, how does light move from the light bulb, to the mirror, and into your eyes?
    --
    Produced in collaboration with PBS Digital Studios: / pbsdigitalstudios
    --
    Want to find Crash Course elsewhere on the internet?
    Facebook - / youtubecrashc. .
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    Support CrashCourse on Patreon: / crashcourse
    CC Kids: / crashcoursekids

Комментарии • 425

  • @crashcourse
    @crashcourse  Год назад +17

    We made quiz questions to help you review the content in this episode! Find them on the free Crash Course App!
    Download it here for Apple Devices: apple.co/3d4eyZo
    Download it here for Android Devices: bit.ly/3TW06aP

  • @theangmister
    @theangmister 7 лет назад +949

    WE NEED CRASH COURSE MATHS

    • @ayadimishra
      @ayadimishra 7 лет назад +15

      Angelo Thavaratnarajah I second this!!

    • @malhaar5880
      @malhaar5880 6 лет назад +16

      U goddamn right

    • @niaschim
      @niaschim 6 лет назад +23

      3blue1brown in the mean time

    • @thebge1237
      @thebge1237 6 лет назад +5

      Try searching for the youtube channel y mx+c
      The guy teach malaysian math but i think it will still teach you something

    • @thebge1237
      @thebge1237 6 лет назад +2

      Btw he speak english

  • @ThePositiveTarot
    @ThePositiveTarot 5 лет назад +97

    I sometimes watch the videos twice... The first time I just listen and get what I can get, which usually is a broad idea of what the topic is about, then watch it again the second time while concentrating, pausing, contemplating and taking screenshots as necessary

  • @gergeapeach
    @gergeapeach 6 лет назад +460

    Two helpful hints: Watch with captions and at 0.75x speed.
    And pause often to think if needed.

    • @cait_frb
      @cait_frb 5 лет назад +3

      Thank you

    • @owencoukell388
      @owencoukell388 5 лет назад +41

      1.5 speed with no captions: Badass mode

    • @itswarhawk
      @itswarhawk 5 лет назад +13

      @@owencoukell388 Ur cool but I don't wanna fail my exam lol

    • @ori5278
      @ori5278 5 лет назад +1

      @@owencoukell388 ok

    • @ori5278
      @ori5278 5 лет назад +3

      That doesnt really help apart from the pause often part

  • @sofiatovedal7663
    @sofiatovedal7663 5 лет назад +373

    Why do everyone complain about the speed of her speech? All crash-course videos are like this, it's the whole point to squeeze a bunch of information into a short video.

    • @ameerhamza4816
      @ameerhamza4816 5 лет назад +15

      But it's not possible. People who don't know can't get this so fast

    • @justfr4nk468
      @justfr4nk468 5 лет назад +7

      exactly, at least it's not boring as a 3-hour class, and it's the same data but faster and more simplified

    • @symbolofpeace.3846
      @symbolofpeace.3846 4 года назад +34

      Oh come on friends... You can slow down the video by yourself ...
      I also felt that it's too fast, but there's way to solve the issue.... They are really doing a good work.

    • @aksharaa5376
      @aksharaa5376 4 года назад +22

      @@symbolofpeace.3846 i definitely agree with you. it's best to fix the problem by fixing ourselves, rather than blame others. crashcourse does really put in a lot of effort, and we should appreciate it, rather than complaining

  • @sarahzhao9347
    @sarahzhao9347 7 лет назад +276

    She was wrong that the image is always upside down for converging/convex lenses. If the object is closer than the focal point, you will end up with a vitual image that is upright.

  • @millie9858
    @millie9858 5 лет назад +65

    When you got a science test next and didn’t understand anything in class

  • @brittniep9219
    @brittniep9219 4 года назад +32

    If you struggle with following along at her natural speed (to make an information packed short video), I recommend choosing the 75% speed option. It is still relatively quick but much easier to follow along with for those of us that aren't as fast of auditory learners! :)

  • @kiasmorningstar
    @kiasmorningstar 7 лет назад +72

    I personally struggle with holding thoughts more than 15 to 20 seconds at a time. The quick pace of this series is just right to hold my attention, and I feel the amount of information is just right. I have sat through these traditional courses, and after waiting for people who don't understand to ask all their questions I am already thinking of something else other than the subject matter. Thank you crash course.

  • @jebus6kryst
    @jebus6kryst 7 лет назад +57

    The Star Wars reference was awesome.

  • @Chris-vx9qp
    @Chris-vx9qp 7 лет назад +74

    I learned and easily consumed more knowledge from this 10 minute video than I did in a week's worth of intense focus towards this exact subject in science class.

  • @darknightofthesoul8980
    @darknightofthesoul8980 7 лет назад +389

    If only more ants had umbrellas.

    • @fossilfighters101
      @fossilfighters101 7 лет назад

      +

    • @AlexandreG
      @AlexandreG 6 лет назад +5

      Dark Night of the Soul now I understand I was an evil kid

    • @tiaradsouza2072
      @tiaradsouza2072 6 лет назад

      Dark Night of the Soul I.

    • @dapet2258
      @dapet2258 4 года назад +4

      I did that with other bugs. I wish other bugs had umbrellas too.

  • @avinashbinand9272
    @avinashbinand9272 6 лет назад +22

    I'm so glad this channel exists. It's the only thing apart from my dad keeping me from failing physics.

  • @edwardbackman744
    @edwardbackman744 7 лет назад +248

    Why do I even watch these I can only follow them for the first 3 minutes

    • @chingalingaling
      @chingalingaling 5 лет назад +6

      Pause button. Notebook.

    • @kurtpace1545
      @kurtpace1545 5 лет назад

      I know cause they are thrash

    • @ThePositiveTarot
      @ThePositiveTarot 5 лет назад +3

      Slow down and/or repeat

    • @aster4405
      @aster4405 5 лет назад +7

      @@kurtpace1545 no u

    • @shanthala1345
      @shanthala1345 5 лет назад +9

      @@kurtpace1545 they'r not!😭iam surviving high school! thanks to crash course.

  • @flamedragon07
    @flamedragon07 4 года назад +6

    I agree. I love the Rogue One and the Last Jedi Prophecy references. Keep up the wonderful work. Yes, I wish they had Crash Course Math also. I could use the math help.

  • @adventure9119
    @adventure9119 7 лет назад +17

    I love the Rogue One reference :D

  • @Emily-on9jq
    @Emily-on9jq 6 лет назад +33

    You know you've watched too much CrashCourse when you recognize that the animation is Scout Finch.

  • @Dribbles88
    @Dribbles88 7 лет назад +4

    Love it!!! We cover this in Physics 223 but in great detail. Great review!! THANKS!! Keep them coming please!

  • @jahsoka8307
    @jahsoka8307 5 лет назад +20

    1:16 Last Jedi prophecy!!! They knew🤔

  • @andrianinikolaou6618
    @andrianinikolaou6618 7 лет назад +6

    Great video! Such videos are extremely important to me, as my school teacher is useless 😂 We this I finally got to understand reflection. Very helpful! 😊❤

  • @conormahon845
    @conormahon845 5 месяцев назад +2

    Thank you for giving the ant an umbrella

  • @erickgudin
    @erickgudin 4 года назад

    great! all your videos are so clear and useful!

  • @dianaanonymous5794
    @dianaanonymous5794 5 лет назад +5

    THANK YOU THIS HAS HELPED ME IMMENSELY

  • @andomadsen3743
    @andomadsen3743 7 лет назад +3

    Turning a blurry world into a high-definition experience... yep, very much an accurate summary of my experience each time I update my spectacle prescription.

  • @bridger1221
    @bridger1221 Год назад +2

    This video alone got me through grade 10 optics! Thank you so much crash course!

  • @user-yc7ub3dj5t
    @user-yc7ub3dj5t 8 месяцев назад +1

    This video has taught me more than the hours worth of lectures I attended for this part of Physics lol, channel never fails

  • @orianmenashe8661
    @orianmenashe8661 6 лет назад

    You guys are amazing this video helped me alot with my physics exam!!!

  • @TGC40401
    @TGC40401 7 лет назад +2

    I like this show. Keep it coming lol... Although I've already done lots of this stuff lol

  • @frhneil1463
    @frhneil1463 6 лет назад +1

    Great video! I have a physics exam tomorrow and i just not into reading tonight, and thought that this video explain almost everything from my text book! Greater ways to study,
    P/s : read that some people thought that the teacher is talking too fast. I think that's not a problem though, some people need to study in a fast way, so they need to make a video no longer than 10 minutes. For those who can't catch up what she is saying (which happens to me too) I recommend you guys to pause the video to digest all of the information in your mind before moving on to another new information.
    Have a great day ! ♡
    And the animation is so cute!

  • @clintgolub1751
    @clintgolub1751 6 лет назад +2

    This was exactly what I was looking for!

  • @howareyou9158
    @howareyou9158 7 лет назад

    I have been waiting for this topic for one year!

  • @olohijeozolua8366
    @olohijeozolua8366 4 года назад +3

    I love listening to you 😍😍😍 so much to learn 😍😍😍

  • @MrJayPuff
    @MrJayPuff 5 лет назад

    Awesome job!

  • @lilit3552
    @lilit3552 7 лет назад

    Thank you so much, this really helps me.

  • @Jana-cw8xf
    @Jana-cw8xf 5 лет назад

    really helped me understand! thanks x

  • @yousefabdelgaber7498
    @yousefabdelgaber7498 4 года назад +1

    This was the first crash course physics video I could keep up with first go

  • @zainababdullah6690
    @zainababdullah6690 6 лет назад +3

    Thanks so much 💙

  • @Zikiss
    @Zikiss 5 лет назад +2

    0:21 Love the Mirror Master appearance.

  • @Hamraali
    @Hamraali 10 месяцев назад

    great explanation!

  • @ArianaCabello
    @ArianaCabello 5 лет назад +2

    They just had to use the rogue one reference which made my night 😂😂😂

  • @whatthefunction9140
    @whatthefunction9140 7 лет назад +127

    OMG I thought that robot was wacking it for a sec. 0:56

  • @pasteltwighlights9437
    @pasteltwighlights9437 4 года назад +23

    i had to watch this on my online class 😭

  • @TheFireflyGrave
    @TheFireflyGrave 7 лет назад +1

    I've never tried noticed that straw illusion, one day I'll have to give it a try... maybe right now.

  • @sookiesister312
    @sookiesister312 4 года назад

    This is very helpful thank you

  • @FishTankEnjoyer
    @FishTankEnjoyer 2 года назад

    You did very good!

  • @fawazsm
    @fawazsm 4 года назад +2

    5:23 focal length of lens depends on refractive index also ... the relation given there is that of a mirror.

  • @sfruizmiranda
    @sfruizmiranda 5 лет назад

    I LOVED THE MIRROR MASTER REFERENCE!

  • @princyprincy9649
    @princyprincy9649 4 года назад

    So helpful for revise 🤗🤗thank u

  • @tapansapre8578
    @tapansapre8578 6 лет назад

    Really informative video!!!!!!!!!!!!!

  • @yeknomican
    @yeknomican 6 лет назад +2

    The whole point of "Crash Course" is that it is presented in a "crash" of information. The whole reason why it works is as a supplement to proper lectures, or with liberal use of either the pause button, or the replay button. This has been true since the beginning of this channel. - verdatum

  • @valerianmp
    @valerianmp 7 лет назад +1

    A good thing to start a day

  • @hayakiliyanni9920
    @hayakiliyanni9920 4 года назад +5

    she has a good pronounce in English
    and we have to slow the speed to understand it
    actually the correct pronounciation make it difficult for me but still i can understand the way of teaching.
    and i can understand everything about light in this video

  • @StillMintTea
    @StillMintTea 4 года назад +8

    That unfinished 5x5 always distracts me ( the cube, ppl)

  • @shamnamuneer6597
    @shamnamuneer6597 6 лет назад

    Crash course is my favourite channel 😍😍😍😍

  • @ollieoreoo
    @ollieoreoo 5 лет назад +1

    Bombed my first optics test so I'm here XD thank u

  • @helenehamamji8363
    @helenehamamji8363 5 лет назад

    Thank you so much for this video, it helped me a lot! But it would be better if it was a little bit slower because it was kind of difficult for me. Otherwise the video is good.
    Have a nice day !

  • @thomnasilikeswordfighting5506
    @thomnasilikeswordfighting5506 7 лет назад

    great video! :D

  • @shawnsea624
    @shawnsea624 3 месяца назад

    Thanks!

  • @miguelsobrevilla7673
    @miguelsobrevilla7673 5 лет назад +1

    Appreciate, I have an astigmatism. Thanks.
    The angle is the result of crying, then a promise. Side rear mirrors are based on this theorem.

  • @josiahmongru8197
    @josiahmongru8197 7 лет назад

    cc is a life saver

  • @Robotcazplays
    @Robotcazplays 7 лет назад

    Exam in two days, this is on it and this really helps Thanks.

  • @Vipin-kq5mg
    @Vipin-kq5mg 5 лет назад +2

    Thank you so much... You saved my life... Wonder Woman 😍😍😍😍

  • @160p2GHz
    @160p2GHz Год назад

    Wish I'd had this resource when I was first learning this :*D

  • @ayadimishra
    @ayadimishra 7 лет назад +14

    CRASH COURse MATH PLEASE 😢😢
    now that we have CS , MATH NEXT!!😣
    ...btw, thank you for CS 😊

  • @zachydrogeo
    @zachydrogeo 5 лет назад +20

    now I'm wondering if optometrists know as much physics as engineers...

    • @veronicas8270
      @veronicas8270 4 года назад +4

      I was thinking the same thing! They must know something about all of the lenses they switch in front of my eye. Probably not as much as engineers, but they must know stuff about light and lenses.

    • @brittniep9219
      @brittniep9219 4 года назад +4

      Optometrists do have to take physics! They then specialize differently than engineers.

  • @sunnysingh-lh8nw
    @sunnysingh-lh8nw 7 лет назад +2

    She is a wonderful teacher that makes the topic very clear.... She is flawless..... Love crash course physics because of her. Thanks

  • @vincentpranayj8599
    @vincentpranayj8599 6 лет назад

    Awesome

  • @sfruizmiranda
    @sfruizmiranda 6 лет назад

    I loved the Mirror Master reference

  • @geoffreypagcaliwagan3024
    @geoffreypagcaliwagan3024 7 лет назад +8

    had a test about this last monday. wouldve been really helpful :(

  • @gabrielserafin5215
    @gabrielserafin5215 6 лет назад

    The infinite Rey pun has so much more meaning now !

  • @satyamsingh9695
    @satyamsingh9695 5 лет назад

    Thank you Very much Mam😊😊😊

  • @FireBucket
    @FireBucket 7 лет назад +1

    Will you guys do an episode about shadows and darkness ?

  • @ahmedabdalla8849
    @ahmedabdalla8849 7 лет назад

    At 7:02 you stated that convex lenses always create upside down images. But don't they create erect ones if the object is with a focal length of the lens?

  • @TheSammycorreia
    @TheSammycorreia 7 лет назад +1

    You guys should do a series on marketing ... Great vids

  • @arielthomas8737
    @arielthomas8737 4 года назад +3

    0:47 is looking more likely every day

  • @shashwatsingh9698
    @shashwatsingh9698 7 лет назад +1

    umm....isnt the magnification for lenses v/u instead of -v/u in general...
    also i think the sign in the lens formula is wrong.

  • @volume8831
    @volume8831 5 лет назад +2

    What’s good is that you can go back and listen again if you get distracted compared to skl Lol.

  • @satyamsingh9695
    @satyamsingh9695 5 лет назад

    You Saved my Literally

  • @AyeshaKhan-gp9on
    @AyeshaKhan-gp9on 7 лет назад

    I'm soooooooooo glad that Shini went slow this time. In the videos on electricity, magnetism, electromagnetism and Maxwell's equations, all she did was show equations at a breakneck speed.

  • @nat29_
    @nat29_ 4 года назад +1

    want a lesson for separation of compound in mixtures
    and composition of a mixture

  • @jamaluddin9158
    @jamaluddin9158 7 лет назад

    hang on, doesn't convex lens form a virtual image when the object is placed between focus and pole?

  • @renjunsriceroll
    @renjunsriceroll 7 лет назад +1

    i got lost at reflection and refraction when its already like my third time learning and two exams of that topic

  • @user-eq7mc4vy6b
    @user-eq7mc4vy6b 7 лет назад

    Thank you very much. There are some of them 1; 17; 15; 25 I want the rest of the episodes translated into Arabic.

  • @andromeda8325
    @andromeda8325 6 лет назад

    Cool!!!

  • @thomaskoning3985
    @thomaskoning3985 2 года назад

    This video taught me more than my physics professor in a month

  • @geethanjalinagiri9714
    @geethanjalinagiri9714 5 лет назад +1

    What my teacher couldn’t do in ten weeks, crash course did in less than ten minutes

  • @shyambhadra2009
    @shyambhadra2009 6 лет назад

    Do you have any videos about convex and concave mirrors?

  • @ekim5589
    @ekim5589 7 лет назад

    Question: for the last two sentences, she said that if the "image is upside down like in our converging lens, then the height is a negative value. And the ratio of the image distance to the object distance is also negative" If the equation is m [magnification] = hi/ho= -di/do, then how can this be true?
    If the image height is negative, shouldn't the image distance to object distance be positive to maintain the original equation?

    • @hidude1354
      @hidude1354 7 лет назад

      You are correct that magnification can be shown from height and distance, but your formulas are incorrect. For height, it is: -(Object Height/Image Height). And for distance: -(Object Distance/Image Distance). Therefore, both equations are equivalent.

  • @spanishlatte9422
    @spanishlatte9422 4 года назад

    Isn't it a concave mirror is the converging lens while the convex the diverging? I'm confused.

  • @smotmot
    @smotmot 5 лет назад

    Is there a mistake at 3:15? Says the higher the index of refraction the smaller the angle, shows the opposite.

  • @ThePhoenixpaw
    @ThePhoenixpaw 7 лет назад

    So, how do you calculate "Dioptre"?

  • @latifurrahmanzihad
    @latifurrahmanzihad 7 лет назад

    nice

  • @joshuamitchell5530
    @joshuamitchell5530 7 лет назад +2

    7:03, not exactly true as a convex lens can produce a virtual image which is upright.

    • @hidude1354
      @hidude1354 7 лет назад

      In terms of Real Images, she is correct.

  • @science-y9209
    @science-y9209 4 года назад +1

    Do tell me if i have my fact wrong but it's
    1/v-1/u=1/f
    in my book and getting confused now cuz even when i googled it ..but most of them consented with mine but some of them had that formula too ...😐

    • @Shreyasiiiii
      @Shreyasiiiii 4 года назад +1

      This formula is correct...
      But,, it's called lens formula..n it's applicable to spherical lenses...
      N mirror formula is:
      1/v + 1/u = 1/f

  • @VNCCentral
    @VNCCentral 5 лет назад

    Do nọt like the speaker's way. Crazy

  • @matthewhall319
    @matthewhall319 7 лет назад +23

    CrashCourse should do a Crash Course to how you make Crash Course.

  • @ahhhmadXD
    @ahhhmadXD 7 лет назад

    i cannot see far that good, so I need glasses. when i watch to far away via mirror near me, why isnt the image clear? as light comes from reflection on mirror

  • @ANITBIOTICS
    @ANITBIOTICS 2 года назад

    crash course: the only thing that is stopping me from failing my class homework

  • @noahkirkpatrick8912
    @noahkirkpatrick8912 5 лет назад

    Nice voice good vid

  • @TheLowstef
    @TheLowstef 7 лет назад

    The info box at about 5:30 is wrong. The focal length is half the radius for mirrors, not lenses. The lens formula is more complicated