Photoelectric Effects and deBroglie Equation: Practice Problem & Solution
Assertion (A): The stopping potential increases, when frequency of incident rays are increased. Reason (R): Stopping potential is directly proportional to the frequency of incident radiation.
Short Solution (Best for NEET):
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:
Concept: Einstein's photoelectric equation.
Formula: \(eV_s = hf - \phi_0\) or \(V_s = \frac{h}{e}f - \frac{\phi_0}{e}\) where \(f\) is frequency and \(\phi_0\) is work function.
Solution: From the formula, as frequency \(f\) increases, the stopping potential \(V_s\) also increases. So (A) is true. However, \(V_s\) is linearly dependent on \(f\) with an intercept of \(-\frac{\phi_0}{e}\) (unless \(\phi_0 = 0\)), not directly proportional. So (R) is false.
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