CUET Preparation Today
The work function of a substance is 4 eV. What is the approximate longest wavelength of light that can cause photo-emission ? |
309 nm 209 nm 109 nm 9 nm |
309 nm |
$λ_{th}=\frac{hc}{\phi}=\frac{12400}{4}Å=3100Å=310nm$ $λ≤λ_{th}⇒λ≤310nm$ |
