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: D
Explanation
The work function (\(\phi\)) of a metal is defined as: \(\phi = hf_0\) \(f_0 = \frac{\phi}{h}\) \(\phi = 3.0 eV = 3.0 \times 1.6 \times 10^{-19}\) = \(4.8 \times 10^{-19} J\) \(f_0 = \frac{4.8 \times 10^{-19}}{6.6 \times 10^{34}}\) = \(0.727 \times 10^{15} s^{-1}\) = \(7.27 \times 10^{14} s^{-1}\) \(\approxeq 7.3 \times 10^{14} Hz\)
