Question
An experiment is set up to demonstrate the diffraction of water waves in a ripple tank. The waves pass through a gap of width w and some diffraction of the waves is observed. The wavelength of the waves is now doubled.
What is the new gap width needed to cause the same amount of diffraction as before?
(A) 0.5w
(B) w
(C) 2w
(D) 4w
Answer/Explanation
Ans: C
Question
A continuous progressive water wave in a ripple tank passes through a gap in a barrier and diffracts.
The width of the gap is greater than the wavelength of the wave.
Which change causes the wave to spread over a larger angle as it passes through the gap?
(A) a small decrease in the wavelength of the wave
(B) a small decrease in the width of the gap
(C) a small increase in the frequency of the wave
(D) a small increase in the height of the barrier
▶️Answer/Explanation
Ans: B
Question
A ripple tank and a barrier with a single gap are used to demonstrate the diffraction of surface
ripples on water. Initially, the wavelength of the ripples is five times smaller than the gap in the barrier.
Which change increases the amount of diffraction observed?
(A) double the amplitude of the ripples
(B) double the width of the gap
(C) halve the frequency of the ripples
(D) halve the wavelength of the ripples
▶️Answer/Explanation
Ans: C
Question
Light of frequency \(6.7 \times 10^{14}\)Hz in a vacuum is incident normally on a diffraction grating that contains \(4.0 \times 10^5\) lines \(m^{–1}\). What is the angle between the adjacent second and third order intensity maxima?
A 12 \(\circ\)
B 21\(\circ\)
C 33\(\circ\)
D 54\(\circ\)
▶️Answer/Explanation
Ans A