Communication in the submarines is using infra waves.

The unit of frequency is __________.

The sounds with frequencies greater than 20 kHz are called _____.

• The audible frequency range is 20Hz to 20KHz.
• The sound with frequencies less than 20Hz is called infrasound.

An increase in wavelength makes a sound wave _______.

• Sounds with frequencies below 20Hz are infrasound.
• Wave speed= frequency × wavelength 

Sound travels faster in _________ .

Sound cannot travel through _________.

A child was observing the thunderstorm from the glass window of his room. What would he feel first?

Sound with high frequency is called as   ________.

Sounds with frequencies less than 20Hz are called infrasound.

Metal cracks are detected using ________ sounds.

• Ultrasound or high frequency sound waves is transmitted into materials to characterize the material or for crack detection.

Animals like elephants communicate in _______ sounds.

Sound which has less frequency are called as ________ sounds

Sounds which have frequencies more than 20kHz are called ultrasounds.

A sound wave traveling at a speed of 1000 m/s has a frequency of 1 kHz. Its wavelength is ___ m.

2.5 kHz = ____ Hz.

In which of the following mediums does the sound propagate at the highest speed?

The picture below indicates a _____.

Shock waves carry ____.