Question

A sound wave of wavelength 90 cm in glass is refracted into air. If the velocity of sound in glass is 5400 m/sec, the wavelength of the wave in air is –

• A. 55 cm
• B. 5.5 cm
• C. 55 m
• D. 5.5 m

Answer 1

Answer: (B)

5.5 cm

Answer 2

Velocity = frequency × wavelength

In glass : 5400 × 100 = n × 90

or n =$\frac{5400 \times 100}{90}$cps

In air: $\frac{330 \times 100}{\lambda}$ = n =$\frac{5400 \times 100}{90}$

l =$\frac{330 \times 100 \times 90}{5400 \times 100}$= 5.5 cm