Physics Help Forum Beam of Light

 Light and Optics Light and Optics Physics Help Forum

 Feb 9th 2010, 09:20 PM #1 Junior Member   Join Date: Jan 2010 Posts: 3 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?
 Feb 10th 2010, 07:41 PM #2 Senior Member   Join Date: Apr 2008 Location: HK Posts: 886 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 __________________ Good results were achieved and the new task is to become a good doctor.
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 using that formula how do i get my frequency with just the wavelength and energy?

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