Rankers Physics

Photoelectric Effects and deBroglie Equation: Practice Problem & Solution

The work function of a surface of a photosensitive material is 6.2 eV. The wavelength of the incident radiation for which the stopping potential is 5 V lies in the: (2008)
X-ray region
Ultraviolet region
Visible region
Infrared region

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:

The energy of incident radiation is $E = W + eV_0 = 6.2 eV + 5.0 eV = 11.2 eV$. The wavelength is $\lambda = \frac{1240 eV nm}{E(eV)} = \frac{1240}{11.2} \approx 110 nm$. This wavelength lies in the ultraviolet region of the electromagnetic spectrum.

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