Question

Ultraviolet light of 6.2eV falls on aluminium surface (work function = 4.2eV). The kinetic energy in joules of the fastest electron emitted is approximately:

• A. $3\times {10}^{-21}$
• B. $3\times {10}^{-19}$
• C. $3\times {10}^{-17}$
• D. $3\times {10}^{-15}$

Answer 1

The correct option is B $3\times {10}^{-19}$

$E=W+K.E$
$K.E=E-W$
$=6.2eV-4.2eV$
$=2eV$
$=3.2\times {10}^{-19}J$