The work function of a surface of a photosensitive material is 6.2 e.V. The wavelength of the incident radiation for which the stopping potential is 5 V lies in the :

Question

$\begin {array} {1 1} (1)\;X-ray\: region & \quad (2)\;Ultraviolet\: region \\ (3)\;Visible\: region & \quad (4)\;Infrared\: region \end {array}$