Sonar - Class 9, Sound

Question 1 Write the full form of SONAR?

Question 2 What is a SONAR?

Question 3 What is the use of sonar?

Question 4 A sonar picks up a return signal after 3 sec.How far away is the object?

Question 5 What is eco-ranging?

Question 6 What is echolocation?

Question 7 How is the bat able to fly at night without colliding with objects?

Question 17 Explain how bats use ultrasound to catch its prey?

SONAR
Sound Navigation and Ranging
It is a device that uses ultrasonic waves to measure the distance,direction and speed of underwater objects.

1)The transmitter produces and transmit ultrasonic waves.These waves travel through water and after striking the objects on seabed,get reflected back and are sensed by the detector.

2)The detector converts the ultrasonic waves into electrical signal which are interpreted.The time taken for the echo to return to ship is measured by sonar apparatus.

3)The distance of under water object is then calculated from time taken by echo to return.The time it takes for an echo to return is used to find out how far away something is.

2d=v*t
d=Total distance travelled by ultrasound
v=speed of sound through seawater
t=time interval between transmission and reception of ultrasound signal.

This method is called Echo-ranging.

It is used to determine the depth of sea and to locate underwater hills,valleys,submarine,icebergs,sunken ships.

Bats fly in darkness of night without colliding with other objects by method of echolocation.

Bats emit high frequency ultrasonic squeaks while flying and listen to echoes produced by reflection of their squeaks from objects in their path.From the time taken by echo to heard,bats can judge the distance of object in their path and hence avoid it by changing the direction.

Bats search their prey at night by echolocation.

Bats emit high frequency ultrasonic squeaks while flying and listen to the echoes produced by reflection of their squeaks from prey like a flying insect.From the time taken by the echo to be heard,bats can judge the distance of insect and hence catch it.

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