True or false questions. 1. Assuming that the temperature of the air is held con

Question

True or false questions.

1. Assuming that the temperature of the air is held constant, the speed of sound in air does depend on the air pressure, to a good approximation.

2. If an air-filled tube of length L is closed at both endsand vibrates in a sound wave normal mode, the wavelength of the mode must satisfy the condition n(/2)=L, where n is a non-negative integer.

3. If an air-filled tube of length L is closed at both ends and vibrates in a sound wave normal mode, the oscillation of the air pressure in the tube musthave a node at both ends of the tube.

4. In a sound wave, there is only a vibration of pressure; there is no vibration of displacement like there is for a vibrating string.

Explanation / Answer

1. speed of sound in air = sqroot(gamma*RT)

where gamma and R are constants, and given T is constant so speed of sound does not depend on pressure for constant temperature

hence this statement is false

2. For closed closed tube

L = lambda/2, lambda, lambda*3/2 ...

L = lambda*n/2

lambda = 2L/n

hence true

3. as there is displacement node at the ends of closed closed tube, there has to be a pressure antinopde at this point

so this statement is false

4. There is vibration of air molecules, which is seen as pressure displacement, so this statement is false

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