Photoelectric Effects and deBroglie Equation: Practice Problem & Solution
10. When the energy of the incident radiation is increased by 20%, the kinetic energy of the photoelectrons emitted from a metal surface increased from 0.5 eV to 0.8 eV. The work function of the metal is: (2014)
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:
Let initial energy be $E$. We have $E = W + 0.5$. When energy is increased by 20%, new energy is $1.2E$. So, $1.2E = W + 0.8$. Substituting $E = W + 0.5$ into the second equation gives $1.2(W + 0.5) = W + 0.8$. This expands to $1.2W + 0.6 = W + 0.8$, yielding $0.2W = 0.2$, which means $W = 1.0 eV$.
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