Ultrasonic waves of frequency 3 × 10⁵ Hz are passed through a medium where speed of sound is 10 times that in air (Speed of sound in air is 300 m/s). The wavelength of this wave in that medium will be of the order of
1 cm
10 cm
100 cm
0·1 cm
Answer is Right!
Answer is Wrong!
This question was previously asked in
UPSC NDA-1 – 2015
Given frequency f = 3 × 10⁵ Hz.
Speed of sound in air v_air = 300 m/s.
Speed of sound in the medium v_medium = 10 × v_air = 10 × 300 m/s = 3000 m/s.
We need to find the wavelength λ in the medium. Using the formula λ = v_medium / f:
λ = 3000 m/s / (3 × 10⁵ Hz) = 3000 / 300000 m = 1/100 m = 0.01 m.
0.01 m × 100 cm/m = 1 cm.
The wavelength of the ultrasonic wave in the given medium is 1 cm.