Question

Ultraviolet radiation of 6.2 eV falls on an aluminium surface (work function 4.2 eV). The kinetic energy of the faster electron emitted is approximately

• A. $3.2\times 10^{- 15}$ J
• B. $3.2\times 10^{- 17}$ J
• C. $3.2\times 10^{- 19}$ J
• D. $3.2\times 10^{- 21}$ J

Answer 1

Answer: (C)

KE of emitted electron is
$E_{K}=h\nu$ -W
$= \, 6.2 \, \text{e}\text{V} \, - \, 4.2 \, \text{e}\text{V} \, = \, 2.0 \, \text{e}\text{V}$
$= \, 2\times 1.6\times 10^{- 19} \, \text{J}$
$= \, 3.2\times 10^{- 19}\text{J}$