Diffraction at a single slit and the central maximum — practice questions

Question 1 · difficulty L1 · recall

Diffraction is most noticeable when aperture size is

• A. many millions of wavelengths with no edges involved
• B. exactly zero only
• C. comparable to the wavelength
• D. independent of wavelength

Question 2 · difficulty L1 · understanding

For a single slit of width a, minima occur approximately when

• A. a cosθ=mλ
• B. a tanθ=λ/2 for all minima
• C. a= m/λ
• D. a sinθ = mλ

Question 3 · difficulty L2 · understanding

The central maximum in a single-slit diffraction pattern is

• A. twice as wide as the adjacent secondary maxima approximately
• B. half as wide
• C. the same width
• D. absent

Question 4 · difficulty L2 · application

If slit width decreases, the diffraction pattern

• A. becomes narrower
• B. spreads out more
• C. does not change
• D. collapses to a geometric ray

Question 5 · difficulty L3 · application

If wavelength increases at fixed slit width, the central maximum

• A. becomes narrower
• B. is unchanged
• C. becomes wider
• D. vanishes

Question 6 · difficulty L3 · application

For a screen distance D and small angles, central maximum width is approximately

• A. λD/(2a)
• B. aD/λ
• C. 2aD/λ
• D. 2λD/a

Question 7 · difficulty L4 · analysis

A slit width is doubled with λ and D fixed. The central maximum width becomes

• A. one-half
• B. twice
• C. four times
• D. unchanged

Question 8 · difficulty L4 · analysis

Why does diffraction place a limit on optical resolution?

• A. Light ceases to be electromagnetic at small apertures
• B. Finite apertures spread point images into patterns rather than perfect points
• C. Mirrors stop obeying reflection laws
• D. Refractive index becomes infinite

Question 9 · difficulty L5 · analysis

A single slit produces its first minimum at angle θ. If wavelength is halved while a is fixed and angles are small, the first-minimum angle becomes

• A. about 2θ
• B. about 4θ
• C. about θ/2
• D. unchanged

Question 10 · difficulty L5 · analysis

Compared with YDSE interference, a single-slit diffraction pattern has

• A. equally intense equally spaced maxima extending indefinitely
• B. no minima
• C. only one geometric bright line with no spreading
• D. a particularly broad and bright central maximum with weaker side maxima