Photoelectric Effects and deBroglie Equation: Practice Problem & Solution

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: $2.0 eV = 2.0 \times 1.6 \times 10^{-19} J = 3.2 \times 10^{-19} J$.