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:
Dual Nature of Radiation and Matter
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.