Question

Running Notes for class 9 physics chapter 12 sound​

Answer 1

Explanation:

The distance between two successive crests or troughs (or) successive compressions and rarefactions is called as wavelength (λ). The SI unit of wavelength is metre (m).

Wavelength

Time period

Time taken by two consecutive compressions or rarefactions to cross a fixed point is called a Time period (T). The SI unit of time in seconds (s).

Frequency

The number of compressions or rarefactions per unit time is called frequency ().

The SI unit of frequency is Hertz. The SI unit is Hertz (s−1)

v

=

1

T

Speed (v), wavelength (λ) and frequency () are related as v=λ

Amplitude

The magnitude of disturbance in a medium on either side of the mean value is called an amplitude (A).

As shown in the figure below, the unit of amplitude will be the density or pressure. Distance between mean position and crest (maximum displacement).

Amplitude (A)

Amplitude (A)

Pitch

The number of compressions or rarefactions per unit time. Directly proportional to frequency.