Question

The air pressure at sea level is $101325Pa$ . At the centre of a rarefaction of a sound wave in air, the pressure is $91000Pa$ . Which is the most likely pressure at the centres of a compression of the same wave?

• A. $91000Pa$
• B. $101000Pa$
• C. $111650Pa$
• D. $121000Pa$

Answer 1

Answer: (C)

Given, air pressure, $p_o=10135p_a$ and pressure at the centre of rarefaction, $p_1=91000pa$
As we know that, during the propagation of sound wave in air pressure varies as

Thus, we have
$p_1=p_0-dp$
$91000=101325-dp$ (putting values)
$\therefore dp=101325-91000$
$=10325pa$
Thus, the pressure at the centre of compression
$p_1=p_0+dp$
$=101325+10325$
$=111650Pa$
Therefore, the most appropriate option is (c)