Question

Which description best explains how a Doppler radar system works?

A.
It reflects waves off of objects, measuring the difference of the waves it sends and receives.
B.
It sends out a set of waves where each wave is preprogrammed to detect a certain kind of object.
C.
It uses an antenna to measure the angle between two or more objects in distant space.
D.
It uses the Doppler effect to raise the pitch of sound waves so objects in distant space can be heard.

Answer 1

a

Step-by-step explanation:

Answer 2

Answer: A. It reflects waves off of objects, measuring the difference of the waves it sends and receives.

Step-by-step explanation:

A Doppler radar uses the Doppler effect when measuring return echoes after having sent a signal (in this specific case microwaves).

In this context the Doppler effect consists of the change in a wave perceived frequency when the emitter of the waves, and the receiver (or observer in the case of light) move relative to each other.

In the case of radars, a microwave signal is sent to a target and then reflected, so that the radar system measures this difference between the sent signal and the reflected signal.

It should be noted that this effect bears its name in honor of the Austrian physicist Christian Andreas Doppler, who in 1842 proposed the existence of this effect for the case of light in the stars. Another important aspect is that the effect occurs in all waves (including light and sound). However, it is more noticeable to humans with sound waves.