Question

The work function of a metal is 3 eV. The color of the visible light that is required to cause emission of photoelectrons is

• A. Green
• B. Blue
• C. Red
• D. Yellow

Hint:

Use the photoelectric equation to relate the energy of incident light to the work function and kinetic energy of emitted electrons. Remember that shorter wavelengths correspond to higher energy photons, which are required to overcome the work function.

Answer 1

The Correct Option is B

\( (KE)_{max} = \frac{hc}{\lambda} - \phi \) 

\( \frac{hc}{\lambda}>\phi \) [for emission] \( \lambda<\frac{hc}{\phi} \) 

\( \lambda<\frac{1242}{3} nm \) 

So blue light option (B)