The tension in a piano wire is 10N. What should be the tension in the wire to produce a note of double the frequency :

(1) 5 N

(2) 20 N

(3) 40 N

(4) 80 N

A string of 7 m length has a mass of 0.035 kg. If the tension in the string is 60.5 N, then the speed of a wave on the string is :

(1) 77 m/s

(2) 102 m/s

(3) 110 m/s

(4) 165 m/s

A second harmonic has to be generated in a string of length l stretched between two rigid supports. Distances from one end where the string has to be plucked and touched are :

(1) Plucked at $\frac{l}{4}$ and touched at $\frac{l}{2}$

(2) Plucked at $\frac{l}{4}$ and touched at $\frac{3l}{4}$

(3) Plucked at $\frac{l}{2}$ and touched at $\frac{l}{4}$

(4) Plucked at $\frac{l}{2}$ and touched at $\frac{3l}{4}$

The tension of a stretched string is increased by 69%. In order to keep its frequency of vibration constant, its length must be increased by :

(1) 20%

(2) 30%

(3) $\sqrt{69}\%$

(4) 69%

The length of a sonometer wire tuned to a frequency of 250 Hz is 0.60 metre. The frequency of tuning fork with which the vibrating wire will be in tune when the length is made 0.40 metre is :

(1) 250 Hz

(2) 375 Hz

(3) 256 Hz

(4) 384 Hz

Two uniform strings A and B made of steel are made to vibrate under the same tension. If the first overtone of A is equal to the second overtone of B and if the radius of A is twice that of B, the ratio of the lengths of the strings is -

(1) 1: 2

(2) 1 : 3

(3) 1 : 4

(4) 1 : 6

Two wires are fixed in a sonometer. Their tensions are in the ratio 8 : 1. The lengths are in the ratio 36 : 35. The diameters are in the ratio 4 : 1. Densities of the materials are in the ratio 1 : 2. If the lower frequency in the setting is 360 Hz. the beat frequency when the two wires are sounded together is :

(1) 5

(2) 8

(3) 6

(4) 10

The first overtone of a stretched wire of given length is 320 Hz. The first harmonic is : 

(1) 320 Hz

(2) 160 Hz

(3) 480 Hz

(4) 640 Hz

The sound carried by the air from a sitar to a listener is a wave of the following type :

(1) Longitudinal stationery

(2) Transverse progressive

(3) Transverse stationery

(4) Longitudinal progressive

Three similar wires of frequency n₁, n₂ and n₃ are joined to make one wire. Its frequency will be :

(1) $n=n_1+n_2+n_3$

(2) $\frac{1}{n}=\frac{1}{n_1}+\frac{1}{n_2}+\frac{1}{n_3}$

(3) $\frac{1}{\sqrt{n}}=\frac{1}{\sqrt{n_1}}+\frac{1}{\sqrt{n_2}}+\frac{1}{\sqrt{n_3}}$

(4) $\frac{1}{n^1}=\frac{1}{n_1^2}+\frac{1}{n_2^2}+\frac{1}{n_3^2}$