Waves - Result Question 3

3. Sound waves travel at $350 m / s$ through a warm air and at $3500 m / s$ through brass. The wavelength of a $700 Hz$ acoustic wave as it enters brass from warm air

[2011] (a) decreases by a factor 10

(b) increases by a factor 20

(c) increases by a factor 10

(d) decreases by a factor 20

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Answer:

Correct Answer: 3. (c)

Solution:

  1. (c) We have, $v=n \lambda$

$\Rightarrow v \propto \lambda$ (as $n$ remains constant)

Thus, as $v$ increases 10 times, $\lambda$ also increases 10 times.