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Old Feb 9th 2010, 09:20 PM   #1
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Beam of Light

Light of wavelength 0.50x10^6m incident on a metal surface ejects electrons with kinetic energies up to a maximum value of 2.0x 10^-19J. What is the energy required to remove an electron from the metal? If a beam of light causes no electrons to be emitted, however great its intensity, what condition must be satisfied by its wavelength?
(The Planck constant = 6.6x10^-34Js, the speed of light = 3.0x10^8ms^-1)

I need help understanding the question. I am not sure how to begin it.
Am i to use the formula E = hf ?
but using that formula how do i get my frequency with just the wavelength and energy?
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Old Feb 10th 2010, 07:41 PM   #2
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You may have to use
Energy = hf + work function
E = hf + hfo

work fuction is the minimum amount of energy to remove an electron from a metal surface which can be expressed in hfo, where fo is the minimum frequecy of photon for photoelectric effect to occur
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Old Feb 13th 2010, 10:11 AM   #3
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speed = frequency * wavelength

This applies to light waves as well as sound, etc.

Originally Posted by Jospeh View Post
using that formula how do i get my frequency with just the wavelength and energy?
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