F11Physics1CLec25B

F11Physics1CLec25B - Physics 1C Lecture 25B "If you...

Info iconThis preview shows pages 1–8. Sign up to view the full content.

View Full Document Right Arrow Icon
Physics 1C Lecture 25B "If you want the rainbow, you gotta put up with the rain." --Dolly Parton
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Outline Refraction review Mirages (TIR). Huygen’s Principle. Prisms. Dispersion. Rainbows.
Background image of page 2
Mirages Mirages occur because of total internal reflection (TIR). Hot air is less dense than cool air. The less dense hot air has a small index of refraction n. The more dense cool air has a higher n. TIR - light in cool air (slow) off of hot air (fast).
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Huygens’s Principle Christiaan Huygens (1629-1695) introduced a geometric construction that helped to understand many practical aspects of propagation of light. In this construction, all points of a wave front are taken as point sources for the production of secondary waves, called wavelets . New position of the wave front after time D t has elapsed is the surface tangent to the wavelets.
Background image of page 4
Huygens’s Principle We can use Huygens’s principle to derive the laws of reflection and refraction. AB is a wave front of incident light. Point A sends out a wavelet toward point D. Point B sends out a wavelet toward point C. Both rays move with the same speed: AD = BC = c D t Let’s isolate congruent triangles ABC and ADC
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Huygens’s Principle ABC and ADC are congruent because they share hypotenuse AC and because AD = BC. We have: cos g = BC / AC and cos g ´ = AD / AC. Therefore, cos = cos ’ and = This gives θ 1 = θ 1 ’ which is the law of reflection
Background image of page 6
Prisms Example An incident ray in air is headed straight towards an equilateral plastic prism ( n = 1.50). The ray is parallel to the bottom of the prism. Use Snell’s Law
Background image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 8
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 12/11/2011 for the course PHYS 1C taught by Professor Smith during the Fall '07 term at UCSD.

Page1 / 21

F11Physics1CLec25B - Physics 1C Lecture 25B "If you...

This preview shows document pages 1 - 8. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online