A metal surface is illuminated by a radiation of wavelength 4500 Å. The rejected photo-electron enters a constant magnetic field of 2 mT making an angle of 90° with the magnetic field. If it starts revolving in a circular path of radius 2 mm, the work function of the metal is approximately:
- 1.36 eV
- 1.69 eV
- 2.78 eV
- 2.23 eV
The Correct Option is A
Solution and Explanation
The correct answer is (A): 1.36 eV
Explanation:
\(\frac{hc}{λ}\) - Ø = ΚΕ........(i)
R =\(\frac{ mv}{Bq}\) = \(\sqrt{\frac{2m(KE)}{Bq }}\) ........(ii)
Putting the values,
Ø ≃ 1.36 eV
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Concepts Used:
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The dual nature of matter and the dual nature of radiation were throughgoing concepts of physics. At the beginning of the 20th century, scientists untangled one of the best-kept secrets of nature – the wave-particle duplexity or the dual nature of matter and radiation.
Electronic Emission
The least energy that is needed to emit an electron from the surface of a metal can be supplied to the loose electrons.
Photoelectric Effect
The photoelectric effect is a phenomenon that involves electrons getting away from the surface of materials.
Heisenberg’s Uncertainty Principle
Heisenberg’s Uncertainty Principle states that both the momentum and position of a particle cannot be determined simultaneously.