A wave travels through two media. In medium 1, its speed is 400 m/s and wavelength is 2 m. In medium 2, the speed is 600 m/s. The wavelength in medium 2 is:
Answer: B
Frequency remains constant. f = v₁/λ₁ = 2400 = 200 Hz. In medium 2: λ₂ = v₂/f = 200600 = 3 m
Q.822Easy
The intensity of a sound wave is inversely proportional to which of the following?
Answer: B
For a point source, intensity I ∝ 1/r². This is the inverse square law for spherical waves
Q.823Easy
A harmonic wave travels along a string with amplitude 2 cm and wavelength 40 cm. If the wave completes 10 oscillations in 5 seconds, what is the wave velocity?
Answer: A
Frequency f = 510 = 2 Hz, λ = 40 cm, v = fλ = 2 × 40 = 80 cm/s
Q.824Easy
The equation of a wave is y = 0.06 sin(100t - 8x), where x and y are in meters and t is in seconds. The wavelength is:
Answer: A
From equation, wave number k = 8 rad/m. λ = 2π/k = 2π/8 = 0.785 m
Q.825Easy
Two waves of equal amplitude and slightly different frequencies are superposed. The resulting pattern is called:
Answer: B
When two waves of slightly different frequencies interfere, alternating constructive and destructive interference produces beats with beat frequency = |f₁ - f₂|
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Q.826Medium
A sound source moves towards a stationary observer with velocity v_s. The observer hears frequency f'. The actual frequency of the source is f. The relationship is:
Answer: B
For source moving towards stationary observer: f' = f × v/(v - v_s), so f = f'(v)/(v + v_s) when rearranged
Q.827Easy
A string of length 1 m is fixed at both ends. The fundamental frequency is 100 Hz. What is the frequency of the third harmonic?
Answer: C
For a string fixed at both ends, f_n = n × f₁. Third harmonic: f₃ = 3 × 100 = 300 Hz
Q.828Medium
A wave on a string has amplitude A = 5 cm and period T = 0.2 s. The maximum velocity of a particle on the string is:
Two identical loudspeakers separated by 2 m emit sound of frequency 340 Hz in phase. If the speed of sound is 340 m/s, constructive interference occurs at:
Answer: D
Constructive interference occurs when path difference = nλ. λ = v/f = 340340 = 1 m, so path difference = 0, 1 m, 2 m, etc.
Q.830Medium
A pipe closed at one end has its fundamental frequency at 200 Hz. The next higher harmonic that can be produced is:
Answer: B
In a pipe closed at one end, only odd harmonics are produced: f, 3f, 5f, etc. Next higher = 3 × 200 = 600 Hz
Q.831Easy
A longitudinal wave has frequency 50 Hz and wavelength 8 m. The wave velocity is:
Answer: A
v = fλ = 50 × 8 = 400 m/s
Q.832Medium
A wave pulse travels along a rope. When it reaches a fixed end, the reflected pulse is:
Answer: B
At a fixed end, the reflected wave undergoes a phase change of 180° (or π radians) due to the fixed boundary condition
Q.833Easy
Standing waves are formed on a string by superposition of two waves traveling in opposite directions with:
Answer: C
Standing waves form from superposition of two waves with equal amplitude, frequency, and wavelength traveling in opposite directions
Q.834Medium
A progressive wave is represented as y = 2sin(100πt - πx/2). The phase difference between particles at x = 1 m and x = 3 m is:
