Question

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

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

Answer 1

The correct option is B $3.2\times {10}^{-19}$

$E_k=E-W_o=6.2-4.2=2.0eV$
$=2.0\times 1.6\times {10}^{-19}=3.2\times {10}^{-19}J$