Refraction of light | Physics | Khan Academy

Light refracts—it bends—when it passes from one medium into another at an angle. Refraction occurs because the phase velocity of light is different in different media. For example, light slows down when it passes from air into glass. This happens because the incoming electromagnetic wave causes electrons in the medium to oscillate, which produces a secondary electromagnetic wave. The resulting wave, which is a superposition of the incoming wave and the secondary wave, has a different phase velocity than c.

Sections:
00:00 - What is refraction?
01:19 - Understanding wavefronts
03:35 - Why does light refract?
05:56 - What does bending of light depend on?
07:20 - Why does light change speed?
08:30 - Constructive and destructive interference
10:54 - Interference causes phase kick back
12:05 - Modeling change in light speed as a continuous phase kick back
13:35 - What causes dispersion?

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[ChiragSonne]

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[justindie]

Wow what a fantastic explanation! I always assumed that light travels slower because it bounces along an indirect path in the medium, the truth is way more fascinating!

[itsmoonsault]

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[literallythenextmessi]

Incredibly informative. Love this method of teaching and the series!

[shashankpriyadarsi]

This physics really makes my head float

[prakashs]

Thank you very much for the video I had some understanding in constructive wave and destructive wave

[DarthJeremy]

i think its funny how teachers still use chalkboards. These animations really help to clarify the more intense subjects. Khan Academy is an invaluable resource for all human beings.

[yahyasheikhnejad]

just imagin that the values of parameters in c=Lamda*Freq are as follows: 10=2*5. then when light enters into a new medium with refractive index n, it will have speen v=c/n=Lamda*Freq. What will be the value Lamda & Freq? how do they change? for example, consider v=c/n=8. Then Lamda*Freq= 2*4 or 1.6*5 or 1.8*4.45?

[mdataullah]

As we know, the speed of light in any medium is constant. Then how can the glass reflect purple and red light fully different direction?

[SumanYadav-wrcn]

Sir please provide lectures on sieve theory

[PSCstudy-hyci]

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