You have a machine that produces pulses of monochromatic electromagnetic radiati

Question

You have a machine that produces pulses of monochromatic electromagnetic radiation. Each pulse has a fixed total energy of 2.5MeV, but you are able to adjust the frequency of the light.

(A) What's the larguest frequency that this machine can produce?

(B) You direct pulses from the machine at a slab of metal and notice that electrons start being ejected at a frequency of fc=5.8 x 1016 HZ. What is the metal's work function?

(C) You direct a pulse with frequency f = 1.0 x 1016 at the metal once per second. How much current (charge/time) does this photo circuit produce?

(D) What is the Broglie wavelength of these ejected electrons?

Explanation / Answer

A)

Emax = hfmax

2.5 x 106 x 1.6 x 10-19 = (6.63 x 10-34) fmax

fmax = 6.03 x 1020 Hz

B)

fc = 5.8 x 1016 Hz

W = metal's work function = hfc = (6.63 x 10-34) (5.8 x 1016 ) = 3.85 x 10-17 J = 240.625 eV

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