Rankers Physics

Photoelectric Effects and deBroglie Equation: Practice Problem & Solution

Ultraviolet radiations of $6.2 eV$ falls on an aluminium surface. Kinetic energy of fastest electron emitted is (work function = $4.2 eV$) (1989)
$3.2 \times 10^{-21} J$
$3.2 \times 10^{-19} J$
$7 \times 10^{-25} J$
$9 \times 10^{-32} J$

Solution Explained:

To solve this problem, we apply the core principles of Photoelectric Effects and deBroglie Equation. Understanding the underlying formula is key to arriving at the correct answer below:

From Einstein's photoelectric equation, $K_{max} = E - \phi = 6.2 eV - 4.2 eV = 2.0 eV$. Converting this energy to Joules: $2.0 eV = 2.0 \times 1.6 \times 10^{-19} J = 3.2 \times 10^{-19} J$.

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