Question

RADAR is used for

• A. Receiving a signal in a radio receiver
• B. Locating submerged submarines
• C. Locating geostationary satellites
• D. Detecting and locating the position of objects such as aeroplanes

Hint:

Think about what RADAR echoes off objects to find their distance and direction.

Answer 1

The Correct Option is D

Break the word RADAR into its full form first: Radio Detection And Ranging. That full form already tells you the job it does.

1. A transmitter sends a short burst of radio waves into the sky.
2. If the wave hits a solid object such as an aeroplane, part of the energy bounces back toward the source.
3. A receiver picks up this echo, and the system notes the time delay and the angle of arrival.
4. Using the known speed of radio waves, the time delay gives the distance to the object, and the angle gives its direction.

Putting distance and direction together lets RADAR detect and locate objects such as aeroplanes, which matches option D.

A radio receiver picking up a broadcast signal is just communication, with no echo or ranging involved, so option A fails. Submarines are tracked underwater with sound based SONAR because radio waves do not penetrate water well, so option B fails. Geostationary satellites are tracked with dedicated satellite tracking methods rather than everyday RADAR, so option C fails.