# Light question .difficulty finding answer

My prof. just gave us about 6 questions on the last chapter of the summer semester, which is on light...he said we could try the question but if we couldnt get it right it was okay....I tried it anyways and I cannot get it....

At what range must electrons in a wire vibrate to emmit microwaves with a wavelength of 1.00 mm? He told us to note next to the question the word charge.

So here's what I did....

I used the equation : speed of light in a vacuum = (wavelength)(frequency)
since I was trying to find f I used the equation f= c/Lambda

f= 3.00 x 1068 m/s
______________
1 x 10 ^ -3 m

= 3 X10 ^11 hz

Then I used the equation e=hf to find the enerty of photon

(6.63 X10 ^-3 Js)(3 X 10 ^11 xs)
= 1.98 x10^-22 J

I'm not sure what the question is asking for really.....

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Gokul43201
Staff Emeritus
Gold Member
The question is poorly worded. At what range of what ?

The frequency of emitted radiation depends on the acceleration of the charge, and the relation is quite hard to derive for someone who is not a physics grad. Perhaps all he wants is f = 3* 10^11 Hz !! I don't see the possibility of getting a range of answers unless one of the conditions imposed is in the form of a range itself. This is true of the acceleration of a harmonically oscillating charge, but that would certainly be beyond the scope of your class.

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HallsofIvy