# NCERT Class 9 Science Solutions: Chapter 12 – Sound Part 2

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Question 1:

Q. What are wavelength, frequency, time period and amplitude of a sound wave?

Wavelength: The distance between two consecutive compressions or two consecutive rarefactions is known as the wavelength. Its SI unit is metre (m).

Frequency: The number of complete oscillations per second is known as the frequency of a sound wave. It is measured in hertz (Hz).

Amplitude: The maximum height reached by the crest or through of a sound wave is called its amplitude.

Question 2:

Q. How are the wavelength and frequency of a sound wave related to its speed?

Speed, wavelength, and frequency of a sound wave are related by the following equation:

Speed Wavelength Frequency

Question 3:

Q. Calculate the wavelength of a sound wave whose frequency is 220 Hz and speed is 440 m/s in a given medium.

Frequency of the sound wave,

Speed of the sound wave,

For a sound wave,

Speed Wavelength Frequency

Hence, the wavelength of the sound wave is 2 m.

Question 4:

Q. A person is listening to a tone of 500 Hz sitting at a distance of 450 m from the source of the sound. What is the time interval between successive compressions from the source?