Advertisements
Advertisements
Questions
How does one explain the emission of electrons from a photosensitive surface with the help of Einstein's photoelectric equation?
Using photon picture of light, show how Einstein’s photoelectric equation can be established.
Advertisements
Solution
n photoelectric effect, an electron absorbs a quantum of energy (hν) of radiation. If this quantum of energy exceeds the minimum energy needed for the electron to escape from the metal surface (work function ϕ0), the electron is emitted with maximum kinetic energy
Kmax = hν - ϕ0
RELATED QUESTIONS
Find the maximum frequency of X-rays produced by 30 kV electrons.
Why should gases be insulators at ordinary pressures and start conducting at very low pressures?
How will the thermionic current vary if the filament current is increased?
An isolated metal sphere is heated to a high temperature. Will it become positively charged due to thermionic emission?
The constant A in the Richardson−Dushman equation for tungsten is 60 × 104 A m−2K−2. The work function of tungsten is 4.5 eV. A tungsten cathode with a surface area 2.0 × 10−5 m2 is heated by a 24 W electric heater. In steady state, the heat radiated by the heater and the cathode equals the energy input by the heater and the temperature becomes constant. Assuming that the cathode radiates like a blackbody, calculate the saturation current due to thermions. Take Stefan's Constant = 6 × 10−8 W m−2 K−1. Assume that the thermions take only a small fraction of the heat supplied.
The wavelength λe of an electron and λp of a photon of same energy E are related by ______.
What do you mean by electron emission? Explain briefly various methods of electron emission.
Consider Figure for photoemission.
How would you reconcile with momentum conservation? Note light (photons) have momentum in a different direction than the emitted electrons.
Name the factors on which photoelectric emission from a surface depends.
The work function of a metal is 2.31 eV. Photoelectric emission occurs when the light of frequency 6.4 × 1014 Hz is incident on the metal surface. Calculate
- the energy of the incident radiation,
- the maximum kinetic energy of the emitted electron and
- the stopping potential of the surface.
