"An organ pipe is 1.5 m long and closed at one end. What are the first three harmonic frequencies of this pipe?"

57.2 Hz, 171.5 Hz and 285.8 Hz

Explanation:

In a pipe, an open end has antinodes while closed ends have nodes.

The distance is between a node and an antinode is an odd multiple of one-quarter of a wavelength.

For the first harmonic,

Also,

where f is the frequency and v is the velocity.

Substitute the value of .

For the second harmonic,

For the third harmonic,

first harmonic = 56.7 Hz

Third harmonic = 170 Hz

Fifth harmonic = 283.3 Hz

Explanation: see attachment

sonar - device which is used to find the submit submarines, sankalp ship. sonar waves consists of a transmitter and detector which are installed in the observation centre on board of a ship. the ultrasonic waves are sent into the sea at high frequency about 1000 khz in all direction.