Question

A metal whose work function is $3.3eV$ is illuminated by light of wavelength $3\times {10}^{-7}$ m. What is the threshold frequency for photoelectric emission? Given Planck's constant $=6.6\times {10}^{-34}Js$.

• A. $0.4\times {10}^{15}Hz$
• B. $0.8\times {10}^{15}Hz$
• C. $1.6\times {10}^{15}Hz$
• D. $3.2\times {10}^{15}Hz$
  

Answer 1

The correct option is B $0.8\times {10}^{15}Hz$

Work function, $W_0=h{\nu }_0=3.3eV=3.3\times 1.6\times {10}^{-19}J$
Therefore, the threshold frequency, ${\nu }_0=\frac{W_0}{h}=\frac{3.3\times 1.6\times {10}^{-19}}{6.6\times {10}^{-34}}=0.8\times {10}^{15}Hz$
Hence, the correct choice is (b).