Homework Help: physics

Posted by A 75- light source consumes 75 of electrical power. Assume all this energy goes into emitted light on Friday, October 21, 2011 at 10:32am.

A 75 W light source consumes 75 W of electric power. Typically only about 5% of this energy is emitted as visible light of wavelength 600 nm. (a) Calculate the frequency of the emitted visible light. (b) How many photons per second of visible light does the source emit? (c) Is the frequency of light the same thing as as the number of photons emitted per second?

physics - drwls, Friday, October 21, 2011 at 11:03am
(a) frequency = c/(wavelength)
(b) 75 W/(h*f)
where f it the frequency and h is Plank's constant.
(c) certainly not. Frequency does not depend upon brightness. Photons per second does.
physics - drwls, Friday, October 21, 2011 at 12:44pm
By the way, your "posted by" name is an incorrect statement, which disagrees with the facts and the question itself. What is that all about?

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