Lecture 27 Thin Lenses Diffraction

Problems due Wednesday 17: 13, 17, 19, WB 25: : diffraction grating 17: ditto 19: skip b WB: 1-9 pictures of interference

Thin lenses A brief detour to cover a topic needed for lab this week.

object image s s’ Converging lens f h h’

Two Lenses The image formed by one lens can be the object for the second lens. For the second lens, s 2 is the distance from the image formed by the first lens and the location of the second lens. f>0 for a converging lens, the only kind we will deal with in lab this week.

Review of Friday Electromagnetic wave

Electromagnetic Waves Slide 25-33

Sinusoidal Waves Single frequency (single color) and single wavelength, λ. TRANSVERSE with B and E perpendicular to the direction of motion. In vacuum velocity = c = 3.00 x 10 8 m/s Right hand rule relates E, B and direction of propagation – E = cB

Sinusoidal Waves Continued Wave traveling in the +x direction with E polarized along the y-axis, and hence B along the z-axis.

Polarization Slide 25-37

Two slit interference Young demonstrated light behaved as a wave. Bright fringes occurred at angles For small angles

Example Two narrow slits 0.04 mm apart are illuminated by light from a HeNe laser (λ = 633 nm). A. What is the angle of the first (m = 1) bright fringe? B. What is the angle of the thirtieth bright fringe? Slide 17-11

The Diffraction Grating Slide 17-12

The Intensity Pattern Due to a Diffraction Grating Slide 17-14

The Fringes Become Very Narrow as the Number of Slits is Increased Slide 17-15

A Diffraction Grating Splits Light into the Wavelengths That Make It Up Slide 17-16

Problems due Today 17: 1, 2, 4, 7, 9, 10, 12 2: speed in glass 4: wavelength in glass 7: two slit interference 9: ditto, given d and y 5 – y 1, find λ 10: two slits given fringe spacing, λ 12: Δr

Problems due Wednesday 17: 13, 17, 19, WB 25: : diffraction grating 17: ditto 19: skip b WB: 1-9 pictures of interference