A metal has a work function of 3.0 eV. What is the threshold frequency of the metal when electrons are just liberated from the metal.(1 eV = 1.6 × 10-19J; h = 6.6 × 10-34Js)
-
A.
4.8 × 10-19Hz -
B.
9.3 × 10-7Hz -
C.
4.8 × 1014Hz -
D.
7.3 × 1014Hz -
E.
9.3 × 1014Hz
Correct Answer: Option D
Explanation
The work function ((phi)) of a metal is defined as:
(phi = hf_0)
(f_0 = frac{phi}{h})
(phi = 3.0 eV = 3.0 times 1.6 times 10^{-19})
= (4.8 times 10^{-19} J)
(f_0 = frac{4.8 times 10^{-19}}{6.6 times 10^{34}})
= (0.727 times 10^{15} s^{-1})
= (7.27 times 10^{14} s^{-1})
(approxeq 7.3 times 10^{14} Hz)