JEE Physics Waves MCQs Set A

Question. Which of the following phenomenon cannot take place with sound waves?
(a) Polarisation
(b) Refraction
(c) Diffraction
(d) Reflection

Answer: A

Question. The speed of sound in air is independent from its
(a) All of these
(b) Phase
(c) Frequency
(d) Amplitude

Answer: A

Question. The waves which cannot travel without medium are
(a) Sound waves
(b) Light waves
(c) Radio waves
(d) X-rays

Answer: A

Question. When a wave propagating through a medium encounters a change in medium, then which of the following property remains same?
(a) Frequency
(b) Wavelength
(c) Amplitude
(d) Speed

Answer: A

Question. A transverse wave travels along x-axis. The particles of medium move
(a) Either along y-axis or z-axis
(b) Along y-axis
(c) Along x-axis
(d) Along z-axis

Answer: A

Question. The phenomenon of sound propagation in air is
(a) An adiabatic process
(b) An isochoric process
(c) An isobaric process
(d) An isothermal process

Answer: A

Question. In a stretched string
(a) Both transverse and longitudinal waves can exist
(b) Only transverse waves can exist
(c) Only longitudinal waves can exist
(d) None of these

Answer: A

Question. Two strings of same material are stretched to the same tension. If their radii are in the ratio 1 : 2, then respective wave velocities in them will be in ratio
(a) 2 : 1
(b) 1 : 2
(c) 1 : 4
(d) 4 : 1

Answer: A

Question. The sound intensity level at a point 4 m from the point source is 10 dB, then the sound level at a distance 2 m from the same source will be
(a) 16 dB
(b) 23 dB
(c) 32 dB
(d) 26 dB

Answer: A

Question. The tones that are separated by three octaves have a frequency ratio of
(a) 8
(b) 16
(c) 6
(d) 3

Answer: A

Question. In a stationary wave
(a) Strain is maximum at nodes
(b) Strain is maximum at antinodes
(c) Strain is minimum at nodes
(d) Amplitude is zero at all points

Answer: A

Question. A 12 m long vibrating string has the speed of wave 48 m/s. To what frequency it will resonate?
(a) All of these
(b) 6 cps
(c) 4 cps
(d) 2 cps

Answer: A

Question. A certain string will resonant to several frequencies, the lowest of which is 200 cps. What are the next three higher frequencies to which it resonants?
(a) 400, 600, 800
(b) 300, 400, 500
(c) 100, 150, 200
(d) 200, 250, 300

Answer: A

Question. The tension in a wire is decreased by 19%. The percentage decrease in frequency will be
(a) 10%
(b) 19%
(c) 0.9%
(d) 0.19%

Answer: A

Question.  An aluminium rod having a length 100 cm is clamped at its middle point and set into longitudinal vibrations. Let the rod vibrate in its fundamental mode. The density of aluminium is 2600 kg/m³ and its Young’s modulus is 7.8 × 10¹⁰ N/m². The frequency of the sound produced is
(a) 2740 Hz
(b) 2350 Hz
(c) 1685 Hz
(d) 1250 Hz

Answer: A

Question. The string of a violin has a frequency of 440 cps. If the violin string is shortened by one fifth, its frequency will be changed to
(a) 2200 cps
(b) 550 cps
(c) 880 cps
(d) 440 cps

Answer: A

Question. A wire of length one metre under a certain initial tension emits a sound of fundamental frequency 256 Hz. When the tension is increased by 1 kg wt, the frequency of the fundamental node increases to 320 Hz. The initial tension is
(a) 16/9 kg wt
(b) 20/9 kg wt
(c) 4/3 kg wt
(d) 3/4 kg wt

Answer: A

Question. In case of closed pipe which harmonic the p^th overtone will be
(a) 2p + 1
(b) 2p – 1
(c) p + 1
(d) p – 1

Answer: A

Question.  The pitch of an organ pipe is highest when the pipe is filled with
(a) Hydrogen
(b) Oxygen
(c) Carbon dioxide
(d) Air

Answer: A

Question. For a certain organ pipe, three successive resonance frequencies are observed at 425, 595, and 765, Hz respectively, Taking the speed of sound in air to be 340 m/s the fundamental frequency of the pipe (in Hz) is
(a) 85
(b) 245
(c) 170
(d) 425

Answer: A

Question. A closed pipe of length 10 cm has its fundamental frequency half that of the second overtone of an open pipe. The length of the open pipe
(a) 30 cm
(b) 40 cm
(c) 20 cm
(d) 10 cm

Answer: A

Question. In resonance tube two successive positions of resonance are obtained at 15 cm and 48 cm. If the frequency of the fork is 500 cps, the velocity of sound is
(a) 330 m/s
(b) 300 m/s
(c) 1000 m/s
(d) 360 m/s

Answer: A

Question. During superposition of two waves of nearly equal frequencies, beats frequency is defined as the
(a) Number of times the resultant intensity becomes maximum or minimum in one second
(b) Sum of frequencies of interfering waves
(c) Average of frequencies of interfering waves
(d) Number of times the resultant amplitude becomes maximum or minimum in one second

Answer: A

Question. A tuning fork of unknown frequency produces 4 beats per second when sounded with another tuning fork of frequency 254 Hz. It gives the same number of beats per second when unknown tuning fork loaded with wax. The unknown frequency before loading with wax is
(a) 258
(b) 254
(c) 250
(d) Can’t be determined

Answer: A

Question. Ten tuning forks are arranged in increasing order of frequency in such a way that any two consecutive tuning forks produce 4 beats per second. The highest frequency is twice that of the lowest. Possible highest and lowest frequencies (in Hz) are
(a) 72 and 36
(b) 44 and 22
(c) 100 and 50
(d) 80 and 40

Answer: A

Question. A tuning fork vibrating with a sonometer having a wire of length 20 cm produces 5 beats per second. The beats frequency does not change if the length of the wire is changed to 21 cm. The frequency of the tuning fork must be
(a) 205 Hz
(b) 215 Hz
(c) 210 Hz
(d) 200 Hz

Answer: A

Question. A tuning fork and an air column whose temperature is 51°C produce 4 beats in one second, when sounded together. When the temperature of air column decreases the number of beats per second decreases. When the temperature remains 16°C only one beat per second is produced. The frequency of the tuning fork is
(a) 50 Hz
(b) 150 Hz
(c) 75 Hz
(d) 100 Hz

Answer: A

Question.  A man standing on a platform observes that the frequency of the sound of a whistle emitted by a train drops by 140 Hz. If the velocity of sound in air is 330 m/s and the speed of the train is 70 m/s, the frequency of the whistle is
(a) 800 Hz
(b) 400 Hz
(c) 260 Hz
(d) 571 Hz

Answer: A

Question. The longitudinal wave can be observed in
(a) Elastic media
(b) Inelastic media
(c) Both
(d) None of these

Answer: A

Question. In a sinusoidal wave, the time required for a particular point to move from maximum displacement to zero displacement is 0.170 s. The frequency of wave is
(a) 1.47 Hz
(b) 2.94 Hz
(c) 0.36 Hz
(d) 0.73 Hz

Answer: A