21. (a) The kinetic energy Kmof the fastest electron emitted is given by Km= hf– Φ= (hc/λ) – Φ, where Φis the work function of aluminum, fis the frequency of the incident radiation, and λis its wavelength. The relationship f = c/λwas used to obtain the second form. Thus, Km=⋅−1240200420eV nmnmeV = 2.00 eV.,where we have used hc= 1240 eV·nm. (b) The slowest electron just breaks free of the surface and so has zero kinetic energy.
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This note was uploaded on 06/03/2011 for the course PHY 2049 taught by Professor Any during the Spring '08 term at University of Florida.