Which of the following metals require ultraviolet light to exhibit the photoelectric effect? the options available: a. cs, work function=1.95ev b. ag, work function=4.74ev c. k, work function=2.29ev d. y, work function=3.10ev

b. AG, work function=4.74eV

Explanation:

Ultraviolet light starts at the end of the visible light spectrum, where violet light ends:

(wavelength of lowest-energy ultraviolet light)

So, the lowest energy of ultraviolet light can be found by using the formula

where

h is the Planck constant

c is the speed of light

Substituting,

And keeping in mind that

This energy converted into electronvolts is

The work function of a metal is the minimum energy needed to extract a photoelectron from the surface of the metal. Therefore, the metals that exhibit photoelectric effect are the ones whose work function is larger than the energy we found previously, so:

b. AG, work function=4.74eV

Because for all the other metals, visible light will be enough to extract photoelectrons.

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