Three sound waves P, Q and R propagate through the same sample of air where the speed…

PHYSICS · Multi-part · CBSE · Physics · Waves · Waves

Problem

Three sound waves P, Q and R propagate through the same sample of air where the speed of sound is

330\,\text{m/s}

. Their frequencies are related by

f_P = 1.5\,f_Q

and

f_R = 0.75\,f_P

. (i) Derive the ratio

\lambda_P : \lambda_Q : \lambda_R

for their wavelengths. (ii) If the wavelength of wave Q in air is

0.40\,\text{m}

, calculate the frequencies of waves P and R. (iii) The three waves now enter helium, in which the speed of sound is

965\,\text{m/s}

. Compute the new wavelength of wave Q and compare it numerically with its wavelength in air.