Sonar and Radar

Q.

There are cracks and flaws in a metallic component used in construction of buildings. Explain how it can be detected? [3 MARKS]

Q.

An ultrasonic wave is sent from a ship towards the bottom of the sea. It is found that the time interval between the sending and the receiving of the wave is 1.5 second.

The depth of the sea [if the velocity of sound in sea water is 1400 m s^-1] is:

1. 700 m

2. 2100 m

3. 1050 m

4. 1400 m

Q.

Measurement of very long distances like the distance of stars from the earth requires some special methods. List few of the techniques used to determine such distances.

Q. The device which uses ultrasonic waves to measure the distance, direction and speed of underwater objects is ___ .

1. SOLAR
2. SOMAR
3. SONAR
4. SUNAR

Q.

Name the waves used for sound ranging. State one reason for their use. Why are the waves mentioned by you not audible to us ?

Q. Special methods adopted to measure large distances is/are

1. Radio echo method
2. Large pulse method
3. parallax method
4. Vernier caliper method

Q.

What is Echocardiography?

Q.

An object is $11km$ below sea level. A research vessel sends down a sonar signal to confirm this depth. After how long can it expect to get the echo? (Take the speed of sound in seawater as $1,520m/s$)

1. 14.47 s

2. 12.20 s

3. 11.13 s

4. 15.30 s

Q.

What is 'SONAR' ? State the principle on which it is based.

Q.

The deepest recorded point below the sea level is in the Mariana trench, Pacific ocean this point is $11km$ below the sea level. A research vessel sends down a sonar signal to confirm this depth. After how long can it expect to get the echo?Take the speed of sounds in seawater as $1520m/s.$

Q.

Define:

SONAR

Q.

Radio echo method is used to determine very long astronomical distances.

1. True

2. False

Q.

A ship sends out ultrasound that returns from the seabed and is detected after $5s$. If the speed of ultrasound through seawater is $1600m/s$, what is the distance of the seabed from the ship?

1. 3.5 km

2. 4 km

3. 5 km

4. 2.5 km

Q.

Radar is able to detect the reflected waves from an enemy aeroplane after a time interval of 0.02ms. If the velocity of the waves is 3 x 10⁸ms^-1, how far is the plane from the radar?

1. 3 x 10⁵ m

2. 3 x 10³ m

3. 6 x 10⁵ m

4. 2 x 10³ m

5. 6 x 10³ m

Q.

Name the technique by which doctors can produce pictures showing the insides of the human body.

Q.

Cryogenics is used in Magnetic Resonance Imaging because at low temperatures, very high resolution images can be formed.

1. True

2. False

Q.
Ultrasonic waves are made to reflect from various parts of the heart and form the image of the heart. This technique is called___

1. electrocardiography
2. MRI scanning
3. X-ray scanning
4. CT scanning

Q.

A ship sends a sonar wave to the sea bed which is flat and measured several times over a large area, One day the reflected sound wave takes longer time than in previous measurements. The possible reason is:

1. The frequency of the sonar wave, generated by the equipment is lower than previous measurements.

2. There is a solid object of large size in the path of sonar wave.

3. The loudness of the sonar wave, generated by the equipment is lower than previous measurement.

4. There is a huge air bubble in the path of sonar wave.

Q. A rocket is moving at a speed of $220m{s}^{-1}$ towards a stationary target, emits a sound of frequency $1000Hz$. Some of the sound reaching the target gets reflected back to the rocket as echo. The frequency of the echo as detected by the rocket is
(Take velocity of sound $=330m{s}^{-1}$)

1. $3500Hz$
2. $4000Hz$
3. $5000Hz$
4. $3000Hz$

Q.

A sonar device on a submarine sends out a signal and receives an echo $5s$ later. Calculate the speed of sound in water if the distance of the object from the submarine is $3625m$.

1. $1250m{s}^{-1}.$

2. $1450m{s}^{-1}.$

3. $1350m{s}^{-1}.$

4. $1550m{s}^{-1}.$

Q. What is the principle of RADAR ? Write the applications of RADAR.

Q. State the principle of Radar. What are the applications of Radar?

Q. is the device used to find the depth of the sea.

1. RADAR
2. SONAR
3. Seismometer

Q. Two canoes are 10 m apart in a lake. Each bobs up and down with a period of 4.0 s. When one canoe is at its highest point, the other canoe is at its lowest point. Both the canoes are always within a single cycle of waves. Determine the speed of the wave.

1. 2.5 m/s
2. 5 m/s
3. 40 m/s
4. 4 m/s

Q. Depth of water is measured by using

1. Diffraction
2. Reflection
3. Refraction
4. Echo sounding

Q.

In a sonar, ultrasonic waves are sent into the sea water and the reflected waves from a sunken ship are received after 2.0 s. If the velocity of waves in sea water is 1450 $m/s$, find the depth of the sunken ship.

1. 2900 m

2. 1450 m

3. 2800

4. 3000

Q.

What is SONAR?

Q. Explain the principle and working of RADAR with neat block diagram.

Q.

What is meant by sound ranging ? Give one use of sound ranging.

Q.

An oil tanker explodes in the sea. At that instant, an aircraft and a submarine were present vertically above and below the oil tanker respectively at equal distances from it. Find the ratio of the time taken by sound waves to reach them. (Speed of sound in air = 340 m/s. The speed of sound in seawater = 1520 m/s)

1. 5.40

2. 4.47

3. 5.57

4. 6.40