As you may well know, placing metal objects inside a microwave oven can generate

Question

As you may well know, placing metal objects inside a microwave oven can generate sparks. Two of your friends are arguing over the cause of the sparking, with one stating that the microwaves "herd" electrons into "pointy" areas of the metal object, from which the electrons jump from one part of the object to another. The other friend says that the sparks are caused by the photoelectric effect. In this problem, we will prove or disprove the latter idea using basic physics. Suppose the typical work function of the metal is roughly 4.360 X 10-19 J (2.722 eV). Calculate the maximum wavelength in angstroms of the radiation that will eject electrons from the metal.Considering that microwave ovens radiate at 2.45 GHz, how would you respond to the debate?

Explanation / Answer

lambda = h*c/E = 6.62*10^-34*3*10^8/4.36*10^-19 = 4.555*10^-7 m = 4555 Ao

this is the maximum wavelength to eject electrons

frequency of microwave is 2.45 GHz

E = h*v = 6.62*10^-34*2.45*10^9 = 16.219*10^-25 J

this is less than the typical work function of the metal...so sparks are not caused by photo electric effect

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