Echoes

Echoes are used to measure _____.

SONAR is based on the principle of

The persistence of hearing for human beings is not more than

Why do we use SONAR in the sea and the RADAR in the air and ground?

"SONAR is used to find the distance of an object in the sea and RADAR is mainly used for air and ground traffic". Mention three other differences between them.

RADAR stands for Radio Detection and ranging and SONAR stands for Sound Navigation and Ranging.

List the differences between SONAR and RADAR.

_____ wave is used for echo depth sounding.

An echo would be heard distinctly if distance of reflector from the observer is less than $8 \mathrm{m}$.

An observer stands at a distance of $850 \mathrm{m}$ from a cliff and fires a gun. After $k \mathrm{seconds}$ he hears an echo. Calculate the value of $k$, if the speed of sound in air is $340 \mathrm{m} {\mathrm{s}}^{-1}$.

A RADAR uses ultrasonic waves to detect objects like enemy planes.

Give full form of SONAR.
(Choose from Sound Navigation and Region, Sound Navigation and Ranging, Sound Navigation and Receiving)

The method used by some animals like bats, tortoises and dolphins to locate the objects by hearing the echoes of their ultrasonic squeaks is known as _____. (reverberation/echolocation)

The technique of obtaining images of the heart by using ultrasound is called _____.

We can hear two sounds distinctly only if there is a time gap of _____$\left(0.1/0.2\right)$ second between them.

A reflection of sound, arriving at the listener in less than $0.1 \mathrm{s}$ after the direct sound is called _____.

In order to distinctly hear two sounds, there must be a time gap of approximately:

Given the time interval between sending and receiving an ultrasonic wave from a ship to the bottom of the sea is $1.5$ seconds, and the velocity of the wave in seawater is $1400 \mathrm{m} {\mathrm{s}}^{-1}$, determine the depth of the sea.

The repeated reflection that results in the persistence of sound is called __________________.

The time of reverberation of a room $A$ is one second. What will be the time (in second) of reverberation of a room, having all the dimensions double of those of room $A$?