If a Doppler radar weather report indicates that clouds are approaching you, the waves received by the Doppler radar must be___________ the waves sent out by the radar.
A. higher in wavelength than
B. higher in frequency than
C. the same frequency as
D. lower in both wavelength and frequency than

Question

If a Doppler radar weather report indicates that clouds are approaching you, the waves received by the Doppler radar must be___________ the waves sent out by the radar.
	A.	higher in wavelength than
	B.	higher in frequency than
	C.	the same frequency as
	D.	lower in both wavelength and frequency than

anonymous · Answer

what do you think?

anonymous · Answer

Any guesses?

anonymous · Answer

umm.. I'm guessing maybe B?

anonymous · Answer

what makes you guess B

anonymous · Answer

idk just kind of guessed.

anonymous · Answer

...then you are a good guesser
the reason why B is correct is because as the object (clouds in this case) the amount of times the waves pass a point (going to the object and back) will increase as the distance shortens, but the wave length remains unaffected.

anonymous · Answer

cool ;) thnk u.

anonymous · Answer

That's actually not quite right... these are microwaves (electromagnetic radiation) we're talking about, so if the frequency goes up, the wavelength goes down.

anonymous · Answer

The answer B is correct, but I just wanted to clarify that point...

anonymous · Answer

Actually, having read that answer through again, I need to make another clarification.  Let's say I am emitting electromagnetic radiation and you are receiving it.  If I am moving closer or farther away from you while emitting the radiation, the frequency I measure will be higher or lower, respectively, than the frequency you measure.  This is called the Doppler effect.  It has nothing to do with how much distance is between us, only with my velocity relative to you.  The high frequency end of the visible spectrum is blue, while the low frequency end is red.  Therefore, as I move toward you, we say that you observe the radiation to be blueshifted.  As I move away, you see redshift.

This principle governs the Doppler radar, as well as the radar guns used by the police to measure the speed of cars on the road, and is the primary evidence that the universe is expanding.

anonymous · Answer

Oops.  fourth line:

"The frequency YOU measure will be higher or lower, respectively, than the frequency I measure"

anonymous · Answer

It also works with sound, think of a car coming towards you with the horn on. It is higher in pitch until the car passes, and then it is lower.