Question
Light of wavelength 3500 Å is incident on two metals A and B whose work functions are 4.2 eV and 1.9 eV respectively. Which metal will emit photoelectrons?

A

B

Both A and B

Neither A nor B
easy
Solution
B
.
The energy of the incident light is
where is the Planck’s constant, is the speed of light in air and is the charge of electron. Substituting the values of and solving we get E = 3.55 eV. Photoelectrons will be emitted from a metal if the energy of the incident light is greater than the work function. Since the work function of metal Bis less than E, metal B will emit photoelectrons.
SIMILAR QUESTIONS
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