Question 1

Which statement about sound propagation is correct?

Accepted Answer

Sound cannot travel through a vacuum.. Sound needs a material medium to transmit vibrations. In a vacuum there are no particles to vibrate and carry the wave. That is why space is essentially silent for sound.

Question 2

What is the SI unit of frequency?

Accepted Answer

Hertz. Frequency counts how many oscillations occur each second. The SI unit for per second is hertz or Hz. A higher frequency generally corresponds to a higher perceived pitch.

Question 3

For sounds of the same frequency, which factor mainly decides loudness?

Accepted Answer

Amplitude of vibration. Loudness is mainly linked to the amplitude of the sound wave. Larger amplitude carries more energy and usually sounds louder. Intensity in simple cases increases with the square of amplitude.

Question 4

Beats are commonly produced when two sound waves have?

Accepted Answer

Slightly different frequencies. Beats occur due to interference of two close frequencies. The loudness rises and falls as the waves alternately reinforce and cancel. This effect is used when tuning musical instruments.

Question 5

A change in the observed pitch due to relative motion between source and listener is called?

Accepted Answer

Doppler effect. The Doppler effect changes the observed frequency when source and observer move relative to each other. Approaching motion generally increases the observed pitch. It is commonly noticed with passing sirens.

Sound — Set 1