83 free MCQs on Waves, each with its own worked answer and explanation. Wave types, superposition, standing waves, Doppler effect, and sound intensity.
Take the timed Waves chapterwise test →83 practice questions on Waves, sorted Easy → Hard. Try each one first, then open its answer page for the worked explanation. Want the full theory first? Read the Waves notes.
A standing wave forms from two identical waves travelling in opposite directions and interfering; nodes (always zero displacement) and antinodes (maximum displacement) stay fixed in place, unlike a travelling wave where the whole pattern moves.
Q1.
In a stationary wave, the distance between a node and the adjacent antinode is:
Q2.
Waves that require a material medium to propagate are called:
Q3.
In a progressive wave, the phase difference between two points one wavelength apart is:
Q4.
The quality (timbre) of a musical note is decided mainly by:
Q5.
The audible range of frequency for a normal human ear is approximately:
Q6.
Sound waves are which type of mechanical waves?
Q7.
Speed of sound in air at room temperature is approximately:
Q8.
The frequency of a sound wave determines its:
Q9.
Amplitude of a sound wave determines its:
Q11.
Which medium transmits sound fastest?
Q12.
The relation between speed, frequency and wavelength of a wave is:
Q13.
Echo is formed due to:
Q14.
Ultrasonic waves have frequency:
Q15.
Beats are produced when two sounds differ in:
Q16.
The Doppler effect describes the change in observed frequency when:
Q17.
As a train approaches you blowing its horn, the pitch you hear:
Q18.
Standing waves are formed by:
Q19.
In a standing wave, points of zero displacement are called:
Q21.
A wave with wavelength 2 m and frequency 100 Hz has speed:
Q22.
SONAR uses which type of waves?
Q23.
In a longitudinal wave, the region of high pressure is called:
Q24.
The time period of a wave with frequency 50 Hz is:
Q25.
Resonance in an air column occurs when:
Q26.
A sonometer wire vibrating at 256 Hz gives 4 beats/s with a tuning fork. When the wire tension is slightly increased, the beat rate falls. The tuning fork frequency is:
Q27.
The speed of sound in air is 340 m/s at 15 °C. The temperature at which the speed rises to 350 m/s is about:
Q28.
A tuning fork gives 5 beats/s with a 480 Hz fork. On being filed slightly the beat rate drops to 3/s. The original frequency of the tuning fork was:
Q29.
A string fixed at both ends vibrates in its third harmonic (three loops) at 300 Hz. Its fundamental frequency is:
Q30.
A tuning fork of 256 Hz and another of 260 Hz are sounded together. Beat frequency is:
Q31.
Speed of sound in air increases with temperature. At 0°C it is 332 m/s. At 20°C approximate speed is:
Q32.
A closed organ pipe has length L. Fundamental frequency is:
Q33.
An open organ pipe has length 0.5 m. Fundamental frequency if speed of sound = 340 m/s:
Q34.
Doppler formula when observer moves toward stationary source:
Q35.
A wave has equation y = 2 sin(4*pi*t - pi*x). Frequency and wavelength:
Q36.
First overtone of a closed organ pipe is the _____ harmonic:
Q37.
The intensity of sound at distance r from a point source is proportional to:
Q38.
A stationary source emits frequency 500 Hz. An observer moves toward it at 34 m/s (speed of sound = 340 m/s). Observed frequency:
Q39.
Transverse wave on string: speed is proportional to:
Q40.
Minimum distance for hearing echo: time for echo > 1/10 s, speed of sound = 340 m/s:
Q41.
What type of interference occurs when two waves arrive at a point with phase difference of pi radians?
Q42.
Sound level in decibels: if intensity doubles, dB increases by:
Q43.
Which of these waves is NOT a mechanical wave?
Q44.
A string of length 1 m is fixed at both ends. Fundamental frequency = 100 Hz. Second harmonic frequency:
Q45.
Reverberation is due to:
Q46.
Speed of sound in a gas is proportional to:
Q47.
In the Doppler effect, when source moves toward stationary observer:
Q48.
A longitudinal wave travels at 340 m/s with wavelength 0.5 m. Frequency:
Q49.
Principle of superposition states that when two waves meet:
Q50.
The second harmonic of an open organ pipe has the same frequency as the third harmonic of a closed organ pipe. The ratio of the length of the open pipe to that of the closed pipe is:
Q51.
A string fixed at both ends has fundamental frequency 220 Hz. To raise the fundamental to 330 Hz by adjusting only the tension, the tension must be multiplied by:
Q52.
A pipe closed at one end has length 0.25 m and the speed of sound is 340 m/s. Its first overtone frequency is:
Q53.
In a resonance column, the first resonance is at 0.20 m and the second at 0.62 m for a 400 Hz fork. The speed of sound is:
Q54.
A pipe closed at one end shows resonances at 300 Hz and 500 Hz with no resonance in between. Its fundamental frequency is:
Q55.
The intensity level of a sound is 60 dB. If its intensity is increased 100 times, the new sound level is:
Q56.
A train approaches a wall at 60 m/s sounding horn at 600 Hz. Speed of sound = 340 m/s. Frequency of echo heard by driver:
Q57.
Standing wave y = 5 sin(4x) cos(200t). Wave speed is:
Q58.
Open pipe has fundamental frequency f. Closed pipe of same length has fundamental frequency:
Q59.
Two open pipes of length L<sub>1</sub> and L<sub>2</sub> (L<sub>1</sub> < L<sub>2</sub>) are sounded together. Beats per second = 5. If fundamental freq of shorter is 100 Hz, L<sub>2</sub>/L<sub>1</sub> equals:
Q60.
A string of linear mass density 0.01 kg/m is under tension 100 N. Wave speed:
Q61.
For a closed pipe, ratio of first overtone to fundamental frequency:
Q62.
A stationary observer hears frequency 660 Hz from a source moving at 44 m/s (v<sub>sound</sub> = 330 m/s). Source was emitting frequency:
Q63.
Power transmitted per unit length by a wave on a string (amplitude A, frequency f, tension T, linear density mu):
Q64.
A vibrating tuning fork is moved in circles. An observer hears frequency variation. This is due to:
Q65.
Bats navigate using echolocation which uses:
Q66.
In a resonance tube experiment, resonance occurs at length 17 cm and again at 51 cm. Speed of sound (frequency = 500 Hz):
Q67.
Sound from two sources of equal amplitude but phase difference delta superpose. Resultant amplitude:
Q68.
A guitar string of length 80 cm is plucked. Fundamental frequency if v = 400 m/s:
Q69.
End correction in an open organ pipe is applied because:
Q70.
A siren of frequency 800 Hz is moving at 40 m/s toward a wall. Speed of sound 320 m/s. Frequency of beats heard by person behind siren:
Q71.
Wave y = 4 cos(t/10) sin(1000t). Frequency of wave and of intensity variation:
Q72.
When sound wave refracts (enters a different medium), which property changes?
Q73.
Number of loops in standing wave on a string of 0.6 m length with lambda = 0.3 m:
Q74.
A source of sound moves toward a fixed wall at speed vs. Speed of sound = v. Frequency of reflected wave as heard by source:
Q75.
Interference of sound waves is observed in:
Q76.
Two tuning forks of frequencies 256 Hz and 260 Hz are sounded together. The number of beats heard per second is:
Q77.
The speed of a transverse wave on a string is √(T/μ). If the tension is increased fourfold, the wave speed becomes:
Q78.
A pipe closed at one end and a pipe open at both ends have the same length. The fundamental frequency of the closed pipe compared with the open pipe is:
Q79.
A source emitting 300 Hz moves toward a stationary observer at 34 m/s (speed of sound 340 m/s). The observed frequency is about:
Q80.
In a stationary wave the wavelength is 40 cm. The distance between two consecutive nodes is:
Q81.
The fundamental frequency of a sonometer wire is inversely proportional to its vibrating length. If the length is halved (tension unchanged), the fundamental frequency:
Q82.
The intensity of a wave is proportional to the square of its amplitude. If the amplitude is tripled, the intensity becomes:
Q83.
An open organ pipe has a fundamental frequency of 200 Hz. Its second overtone (third harmonic) has frequency:
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