228s12-l04

228s12-l04 - Physics 228 Today: Interference Website: Sakai...

Info iconThis preview shows pages 1–7. Sign up to view the full content.

View Full Document Right Arrow Icon
Physics 228 Today: Interference Website: Sakai 01:750:228 or www.physics.rutgers.edu/ugrad/228 We studied interference at some level in 124, so this should be largely review. Monday, January 30, 2012
Background image of page 1

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

View Full DocumentRight Arrow Icon
Inteference Why do we see the colors in the soap bubble? Interference. We will see how this works today. Monday, January 30, 2012
Background image of page 2
EM Waves First: recall the formula for a traveling plane wave of light, moving in the +z direction: ° E = E 0 cos( kz ωt x ° B = B 0 cos( kz ωt y Second: what happens when we have a point source emitting light uniformly in all directions? We get a spherical wave. The wave expands in r, not z, so the argument kz becomes kr. Energy conservation leads to the amplitude decreasing with r, since the area increases as r 2 . ° E ( r, t )= E 0 r cos( kr ωt ) ˆ θ ° B ( r, t )= B 0 r cos( kr ωt ) ˆ φ Monday, January 30, 2012
Background image of page 3

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

View Full DocumentRight Arrow Icon
Multiple Frequencies / Wavelengths The formula for a traveling spherical wave of light, moving in the +r direction: Note: implicit in these formulas we have a single frequency / wavelength of light. We will assume that to start, but we have to eventually think of having multiple frequencies / wavelengths of light at the same time. ° B ( r, t )= B 0 r cos( kr ωt ) ˆ φ ° E ( r, t )= E 0 r cos( kr ωt ) ˆ θ Monday, January 30, 2012
Background image of page 4
Spherical Wave The frst source emits light. The second source emits light ``in phase’’ with the frst source - ``peaks’’ and ``valleys’’ are emitted at the same time From each source. The waves are ``in phase’’ at points a and b, but not at point c. Monday, January 30, 2012
Background image of page 5

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

View Full DocumentRight Arrow Icon
Maxima and Minima At some places the waves add up and you get constructive interference and maxima.
Background image of page 6
Image of page 7
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 19

228s12-l04 - Physics 228 Today: Interference Website: Sakai...

This preview shows document pages 1 - 7. Sign up to view the full document.

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