Question 12 of 23beginner🔧 ApplyNumerical2 marks

A bat emits ultrasonic sound of frequency 1000 kHz in air. If the sound meets a water surface, what is the wavelength of (a) the reflected sound, (b) the transmitted sound? Speed of sound in air is 340 m s−1^{-1} and in water 1486 m s−1^{-1}.

(a)
Answer

Wavelength of reflected sound = 3.4×103.4 \times 10⁻⁴ m (or 0.34 mm)

(b)
Answer

Wavelength of transmitted sound = 1.486×101.486 \times 10⁻³ m (or 1.49 mm)

Explanation

When sound reflects from a surface, it travels back in the same medium (air), so speed remains 340 m/s. When sound transmits into water, it travels in the new medium with speed 1486 m/s. The frequency remains unchanged in both cases as it depends only on the source, not on the medium. Wavelength is calculated using λ = v/f.

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