Answer:
b. AG, work function=4.74eV
Explanation:
Ultraviolet light starts at the end of the visible light spectrum, where violet light ends:
[tex]\lambda=380 nm =3.8\cdot 10^{-7}m[/tex] (wavelength of lowest-energy ultraviolet light)
So, the lowest energy of ultraviolet light can be found by using the formula
[tex]E=\frac{hc}{\lambda}[/tex]
where
h is the Planck constant
c is the speed of light
Substituting,
[tex]E=\frac{(6.63\cdot 10^{-34} Js)(3\cdot 10^8 m/s)}{3.8\cdot 10^{-7} m}=5.23\cdot 10^{-19}J[/tex]
And keeping in mind that
[tex]1 eV = 1.6\cdot 10^{-19}J[/tex]
This energy converted into electronvolts is
[tex]E=\frac{5.23\cdot 10^{-19} J}{1.6\cdot 10^{-19} J/eV}=3.27 eV[/tex]
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.
