Diffraction at a single slit and the central maximum — NEET & JEE 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 L2 · understanding

In single-slit diffraction, the angular position of the first minimum for small angles is approximately given by

• A. $a\theta=\lambda$
• B. $a\theta=\lambda/2$
• C. $a=\lambda\theta^2$
• D. $\theta=a/\lambda$

Question 6 · 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 7 · 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 8 · difficulty L3 · application

If the slit width in a single-slit diffraction experiment is halved while wavelength and screen distance remain unchanged, the central maximum width becomes

• A. twice as large
• B. half as large
• C. four times as large
• D. unchanged

Question 9 · difficulty L3 · application

If the wavelength used in a single-slit diffraction experiment is doubled with slit width unchanged, the angular width of the central maximum approximately

• A. doubles
• B. halves
• C. remains unchanged
• D. becomes one-fourth

Question 10 · 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