A hospital uses an ultrasonic scanner to locate tumours in a tissue. The operating frequency of the scanner is 4.2 MHz. The speed of sound in a tissue is 1.7 km/s. The wavelength of sound in tissue is close to:
4 x 10-4 m
8 x 10-4 m
4 x 10-3 m
8 x 10-3 m
A star which is emitting radiation at a wavelength of 5000Å is approaching the earth with a velocity of 1.50 × 106 m/s. The change in wavelength of the radiation as received on the earth is:
0.25Å
2.5Å
25Å
250Å
A sonometer wire when vibrated in full length has frequency n. Now it is divided by the help of bridges into a number of segments of lengths l1,l2,l3,... When vibrated these segments have frequencies n1,n2,n3,... then the correct relation is:
n = n1+ n2 + n3 + ..
A standing wave having 3 nodes and 2 anti node is formed between two atoms having a distance 1.21Å between them. The wavelength of the standing wave is:
1.21Å
1.42Å
6.05Å
3.63Å
If the amplitude of sound is doubled and the frequency reduced to one-fourth, the intensity of sound at the same point will:
Increase by a factor of 2
Decrease by a factor of 2
Decrease by a factor of 4
Remains unchanged
A wave of amplitude a = 0.2m, velocity v= 360 m/s and wavelength 60 m is travelling along positive x axis, then the correct expression for the wave is:
An observer moves towards a stationary source of sound with a speed th of the speed of sound. The wavelength and frequency of the source emitted are λ and ƒ respectively. The apparent frequency and wavelength recorded by the observer are respectively:
ƒ, 1.2λ
0.8ƒ, 0.8λ
1.2ƒ, 1.2λ
1.2ƒ, λ
The time of reverberation of a room A is one second. What will be the time (in second) of reverberation of a room, having all the dimensions double of those of room A?
2
4
1
The frequency of sinusoidal wave, 0.40 cos (2000t + 0.80) would be:
1000π Hz
2000 Hz
20 Hz
A wave of frequency 100 Hz is sent along a string towards a fixed end. When this wave travels back after reflection, a node is formed at a distance of 10 cm from the fixed end of the string. The speed of incident ( and reflected) wave are:
5 m/s
10 m/s
20 m/s
40 m/s