Diffraction from a Single Slit

Thought QuestionConsider a single slit diffraction pattern. At the

first dark fringe above the middle bright fringe, what is the phase difference between the contribution to the field from the topmost and bottommost edges of the slit?

A : 45 degreesB : 90 degreesC : 180 degreesD : 360 degreesE : None of the above

If we half the slit width, the central bright fringe

a) Becomes widerb) Remains the samec) Becomes narrower

Light impinges on a single slit but suffers no significant diffraction. We conclude that the wavelength of the

light isa. much shorter than the slit width.b. much longer than the slit width.c. on the order of the slit width.

λ = 5 a

λ = a

λ = a/2

λ = a/3

λ = a/5

λ = a/10

KNIFE FIGHTS AND MISSILESMATTHEW 6

26 Behold the fowls of the air: for they sow not, neither do they reap, nor gather into barns; yet your heavenly Father feedeth them. Are ye not much better than they?

34 Take therefore no thought for the morrow: for the morrow shall take thought for the things of itself. Sufficient unto the day is the evil thereof.

Why larger scale features in two-slit interference?

Resolving Power: Two Stars Seen Through a Slit

Rayleigh’s Criterion

Imaging a Star with a Telescope

Circular aperture resolution

D = 22.1sin min

What can a spy satellite resolve?

Low earth orbit: Too much drag below 300 km

Delta IV max payload size ~5 m Very little light in x-ray, deep uv

bands Strong atmospheric absorption below

300 nm. Fairly good transmission in visible band.

Cat’s eyes have pupils that can be modeled as vertical slits. At night, would cats be more successful in

resolving A. Two headlights on a distant carB. Vertically separated lights on the

mast of a distant boatC. If the two sets of lights are the same

distance away, the ability to resolve them would be the same.

Diffraction Gratings (Resolving power means something different here)

𝑅=𝜆

Δ 𝜆

Resolving Power of a Two Slit Pattern

Resolving Power with N Slits

Resolving Power of a Grating