Question

The photoelectric work function for a photo metal is \( 2 \, \text{eV} \). Among the four wavelengths, the wavelength of light for which photoemission does not take place is

• A. 200 nm
• B. 300 nm
• C. 700 nm
• D. 400 nm

Answer 1

The Correct Option is C

The energy of a photon is given by:
\( E = \frac{hc}{\lambda} \) where
\( h \) is Planck's constant, 
\( c \) is the speed of light, and 
\( \lambda \) is the wavelength. 

For photoemission to occur, the energy of the photon must be greater than or equal to the work function \( W_0 \). 
For \( \lambda = 700 \text{nm} \), the photon energy is lower than the work function, meaning no photoemission occurs.