NEET Physics Waves MCQs Set A

Question. Speed of sound wave in air
(a) increases with increase in humidity
(b) decreases with increase in humidity
(c) increases with pressure
(d) is independent of temperature

Answer: A

Question. Change in temperature of the medium changes
(a) wavelength of sound waves
(b) loudness of sound waves
(c) frequency of sound waves
(d) amplitude of sound waves

Answer: A

Question. With propagation of longitudinal waves through a medium, the quantity transmitted is
(a) energy
(b) matter
(c) energy and matter
(d) energy, matter and momentum

Answer: A

Question. Which of the following statements are true for wave motion?
(a) Mechanical transverse waves can propagate through solids only.
(b) Longitudinal waves can propagate through solids only
(c) Mechanical transverse waves can propagate through all mediums.
(d) Longitudinal waves can propagate through vacuum

Answer: A

Question. A sound wave is passing through air column in the form of compression and rarefaction. In consecutive compressions and rarefactions,
(a) there is no transfer of heat
(b) bulk modulus of air oscillates
(c) Boyle's law is obeyed
(d) density remains constant

Answer: A

Question.  A speeding motorcyclist sees trafic jam ahead of him. He slows down to 36 km/hour. He finds that traffic has eased and a car moving ahead of him at 18 km/hour is honking at a frequency of 1392 Hz. If the speeds of sound is 343 m/s, the frequency of the honk as heard by him will be
(a) 1412 Hz
(b) 1464 Hz
(c) 1372 Hz
(d) 1332 Hz

Answer: A

Question.   A fork of frequency 256 Hz resonates with a closed organ pipe of length 25.4 cm. If the length of pipe be increased by 2 mm, the number of beats/sec. will be
(a) 2
(b) 3
(c) 1
(d) 4

Answer: A

Question. Assertion : Doppler formula for sound wave is symmetric with respect to the speed of source and speed of observer.
Reason : Motion of source with respect to stationary observer is not equivalent to the motion of an observer with respect to stationary source.
(a) If both the Assertion and Reason are incorrect
(b) If Assertion is correct but Reason is incorrect
(c) If both Assertion and Reason are correct, but Reason is not the correct explanation of Assertion
(d) If both Assertion and Reason are correct and Reason is the correct explanation of Assertion

Answer: A

Question.  A pipe of length 85 cm is closed from one end. Find the number of possible natural oscillations of air column in the pipe whose frequencies lie below 1250 Hz. The velocity of sound in air is 340 m/s.
(a) 6
(b) 4
(c) 8
(d) 12

Answer: A

Question. When the wavelength of sound changes from 1 m to 1.01 m, the number of beats heard are 4. The velocity of Sound is
(a) 404 m/s
(b) 4.04 m/s
(c) 414 m/s
(d) 400 m/s

Answer: A

Question.  A string is stretched between two fixed points separated by 75.0 cm. It is observed to have resonant frequencies of 420 Hz and 315 Hz. There are no other resonant frequencies between these two. The lowest resonant frequency for this string is :
(a) 105 Hz
(b) 155 Hz
(c) 205 Hz
(d) 10.5 Hz

Answer: A

Question. Two waves of wavelengths 99 cm and 100 cm both travelling with velocity 396 m/s are made to interfere. The number of beats produced by them per second is
(a) 4
(b) 1
(c) 2
(d) 8

Answer: A

Question. Assertion : Two waves moving in a uniform string having uniform tension cannot have different velocities.
Reason : Elastic and inertial properties of string are same for all waves in same string. Moreover speed of wave in a string depends on its elastic and inertial properties only.
(a) If both the Assertion and Reason are incorrect
(b) If Assertion is correct but Reason is incorrect
(c) If both Assertion and Reason are correct, but Reason is not the correct explanation of Assertion
(d) If both Assertion and Reason are correct and Reason is the correct explanation of Assertion

Answer: A

Question.  A train is moving on a straight track with speed 20 ms^–1. It is blowing its whistle at the frequency of 1000 Hz. The percentage change in the frequency heard by a person standing near the track as the train passes him is (speed of sound = 320 ms^–1) close to :
(a) 12%
(b) 6%
(c) 24%
(d) 18%

Answer: A

Question. Two tuning forks with natural frequencies 340 Hz each move relative to a stationary observer. One fork moves away from the observer, while the other moves towards the observer at the same speed. The observer hears beats of frequency 3 Hz. Find the speed of the tuning forks.
(a) 1.5 m/s
(b) 2 m/s
(c) 1 m/s
(d) 2.5 m/s

Answer: A

Question.  The frequency of a sonometer wire is 100 Hz. When the weights producing the tensions are completely immersed in water, the frequency becomes 80 Hz and on immersing the weights in a certain liquid, the frequency becomes 60 Hz. The specific gravity of the liquid is
(a) 1.77
(b) 1.82
(c) 1.21
(d) 1.42

Answer: A

Question. An air column, closed at one end and open at the other, resonates with a tuning fork when the smallest length of the column is 50 cm. The next larger length of the column resonating with the same tuning fork is :
(a) 150 cm
(b) 200 cm
(c) 100 cm
(d) 66.7 cm

Answer: A

Question.  A siren emitting a sound of frequency 800 Hz moves away from an observer towards a cliff at a speed of 15ms^–1. Then, the frequency of sound that the observer hears in the echo reflected from the cliff is : (Take velocity of sound in air = 330 ms^–1)
(a) 838 Hz
(b) 885 Hz
(c) 800 Hz
(d) 765 Hz

Answer: A

Question.  Two similar open organ pipe of length 50 cm and 50.5 cm produce 3 beats per second when sounded together. The velocity of sound in air is
(a) 303 m/s
(b) 151.5 m/s
(c) 330 m/s
(d) 603 m/s

Answer: A

Question. Assertion : The base of Laplace correction was that exchange of heat between the region of compression and rarefaction in air is negligible.
Reason : Air is bad conductor of heat and velocity of sound in air is quite large.
(a) If Assertion is correct but Reason is incorrect
(b) If both the Assertion and Reason are incorrect
(c) If both Assertion and Reason are correct, but Reason is not the correct explanation of Assertion
(d) If both Assertion and Reason are correct and Reason is the correct explanation of Assertion

Answer: A