Question

A sound wave has a frequency of 1 KHz and wavelength 0.8m. The speed of sound will be: (1) 80m/sec (2) 800m/sec (3) 8000m/sec (4) 80cm/sec.

Answer 1

Velocity of Waves

The velocity of waves is given by the simple formula:

$\Large \boxed{\sf v = \lambda f}$

Where

$\lambda$ = Wavelength

$f$ = Frequency

The distance between consecutive crests or troughs is known as wavelength. Its unit is meter (m).

The number of times a wave passes through a given point in one second is known as frequency. Its unit is hertz (Hz).

Here we are given:

$\lambda = 0.8\ m \\\\ f = 1\ kHz = 1000\ Hz$

Hence, the velocity is:

$v = \lambda f \\\\\\ \implies v = 0.8 \times 1000 m/s \\\\\\ \implies v = 800\ m/s$

Thus, the Answer is:

$\huge \boxed{\sf (2)\ v = 800\ m/s}$