NEET Physics Vibrations of String and Organ Pipe MCQs Set A

a)

b)

c)

d)

Answer:

Question: If vibrations of a string are to be increased by a factor of two, then tension in the string must be made

a) twice

b) half

c) four times

d) eight times

Answer: twice

Question: The fundamental frequency of a closed end organ pipe is n. Its length is doubled and radius is halved. Its frequency will become nearly

a) n/2

b) n/3

c) n

d) 2 n

Answer:  n/2

Question:  The fundamental frequency of an organ pipe is 512 Hz. If its length is increased, then frequency will

a) decrease

b) increase

c) cannot be predicted

d) remains same

Answer: decrease

Question: What is the effect of increase in temperature on the frequency of sound produced by an organ pipe?

a) increases

b) decreases

c) no effect

d) erratic change

Answer:  increases

Question:

a) 2.09 s

b) 0.48 s

c) 0.05 s

d) 3.00 s

Answer: 2.09 s

Question: Frequencies of sound produced from an organ pipe open at both ends are

a) even and odd harmonics

b) only odd harmonics

c) only even harmonics

d) only fundamental note

Answer:  even and odd harmonics

Question:

a) 4

b) 6

c) 5

d) 10

Answer: 4

Question: A closed organ pipe (closed at one end) is excited to support the third overtone. It is found that air in the pipe has

a) four nodes and four antinodes

b) four nodes and three antinodes

c) three nodes and four antinodes

d) three nodes and three antinodes

Answer: four nodes and four antinodes

Question:  If there are six loops for 1 m length in transverse mode of Melde’s experiment., the no. of loops in longitudinal mode under otherwise identical conditions would be

a) 3

b) 6

c) 12

d) 8

Answer:  3

More Questions.............................................

Question:  If n₁, n₂ and n₃ are the fundamental frequencies of three segments into which a string is divided, then the original fundamental frequency n of the string is given by

a)

b)

c)

d)

Answer:

Question:  Tube A has both ends open while tube B has one end closed, otherwise they are identical. The ratio of fundamental frequency of tube A and B is

a) 2 : 1

b) 4 : 1

c) 1 : 4

d) 1 : 2

Answer: 2 : 1

Question: If the length of a stretched string is shortened by 40% and the tension increased by 44% then the ratio of the final and initial fundamental frequencies is

a) 2 : 1

b) 1 : 3

c) 4 : 3

d) 3 : 4

Answer: 2 : 1

Question: The number of possible natural oscillation of air column in a pipe closed at one end of length 85 cm whose frequencies lie below 1250 Hz are : (velocity of sound = 340 ms^{– 1})

a) 6

b) 7

c) 5

d) 4

Answer:  6

Question:  The fundamental frequency of a closed organ pipe of length 20 cm is equal to the second overtone of an organ pipe open at both the ends. The length of organ pipe open at both the ends is

a) 120 cm

b) 80 cm

c) 140 cm

d) 100 cm

Answer: 120 cm

Question:

a) 1.22v

b) 0.61v

c) 1.50v

d) 0.75v

Answer: 1.22v

Question: An organ pipe P₁ closed at one end vibrating in its first overtone and another pipe P₂ open at both ends vibrating in third overtone are in resonance with a given tuning fork. The ratio of the length of P₁ to that of P₂ is

a) 3/8

b) 1/2

c) 1/3

d) 8/3

Answer: 3/8

Question:  Length of a sonometer wire between two fixed ends is 110 cm. If the fundamental frequencies are in the ratio of 1 : 2 : 3, then what is the ratio of lengths of these segments of the wire?

a) 6 : 3 : 2

b) 6 : 2 : 3

c) 2 : 3 : 6

d) 3 : 2 : 1

Answer:  6 : 3 : 2

Question:

a) 6.25 N

b) 0.5 N

c) 12.5 N

d) 4.0 N

Answer: 6.25 N

Question:  Choose the false statement(s) about speed of transverse waves on a stretched string.
I. It depends on linear mass density of the string
II. It depends on the tension in the string
III. It depends on the frequency of the wave

a) III only

b) I only

c) II only

d) I, II and III

Answer: III only

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) Assertion is incorrect, reason is correct.

b) Assertion is correct, reason is incorrect

c) Assertion is correct, reason is correct; reason is a correct explanation for assertion

d) Assertion is correct, reason is correct; reason is not a correct explanation for assertion

Answer:  Assertion is incorrect, reason is correct.

Question:

a) 178.2 Hz

b) 200.5 Hz

c) 770 Hz

d) 188.5 Hz

Answer: 178.2 Hz

Question: A sonometer wire supports a 4 kg load and vibrates infundamental mode with a tuning fork of frequency 416 Hz. The length of the wire between the bridges is now doubled. In order to maintain fundamental mode, the load should be changed to

a) 16 kg

b) 4 kg

c) 2 kg

d) 1 kg

Answer: 16 kg

Question:  Two pulses in a stretched string whose centres are initially 8 cm apart are moving towards each other as shown in the figure. The speed of each pulse is 2 cm/s. After 2 s, the total energy of the pulses will be

a) Purely kinetic

b) Purely potential

c) Partly kinetic and partly potential

d) Zero

Answer: Purely kinetic

Question: A stretched wire 60 cm long is vibrating with its fundamental frequency of 256 Hz. If the length of the wire is decreased to 15 cm and the tension remains the same. Then the fundamental freuqency of the vibration of the wire will be

a) 1024

b) 572

c) 256

d) 64

Answer: 1024

Question: A string is stretched between 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. Then, the lowest resonant frequency for this string is

a) 105 Hz

b) 1.05 Hz

c) 1050 Hz

d) 10.5 Hz

Answer: 105 Hz

Question:  The fundamental frequency of an open organ pipe is 300 Hz. The first overtone of this pipe has same frequency as first overtone of a closed organ pipe. If speed of sound is 330 m/s, then the length of closed organ pipe is

a) 41 cm

b) 37 cm

c) 31 cm

d) 80 cm

Answer: 41 cm

Question:  In a standing wave formed as a result of reflection from a surface, the ratio of the amplitude at an antinode to that at node is x. The fraction of energy that is reflected is

a)

b)

c)

d)

Answer:

Question:  Two strings A and B, made of same material, are stretched by same tension. The radius of string A is double of radius of B. A transverse wave travels on A with speed v_A and on B with speed vB. The ratio v_A / v_B is

a) 1/2

b) 2

c) 1/4

d) 4

Answer: 1/2

Question: In the sonometer experiment, a tuning fork of frequency 256 Hz is in resonance with 0.4 m length of the wire when the iron load attached to free end of wire is 2 kg. If the load is immersed in water, the length of the wire in resonance would be (specific gravity of iron = 8)

a) 0.37 m

b) 0.43 m

c) 0.31 m

d) 0.2 m

Answer:  0.37 m