Advertisements
Advertisements
प्रश्न
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.
उत्तर
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
संबंधित प्रश्न
Find the maximum frequency of X-rays produced by 30 kV electrons.
Find the (a) maximum frequency, and (b) minimum wavelength of X-rays produced by 30 kV electrons.
Why should gases be insulators at ordinary pressures and start conducting at very low pressures?
The work function of the following metals is given : Na 2.75 ev, K = 2.3 eV, Mo = 4.17 eV and Ni = 5.15 eV. Which of these metals will not cause photoelectric emission for radiation of wavelength 3300 Å from a laser source placed 1 m away from these metals? What happens if the laser source is brought nearer and placed 50 cm away?
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
If a light of wavelength 330 nm is incident on a metal with work function 3.55 eV, the electrons are emitted. Then the wavelength of the wave associated with the emitted electron is (Take h = 6.6 × 10–34 Js)
Define the work function of a metal. Give its unit.
Photoelectric emission is observed from a metallic surface for frequencies ν1 and ν2 of the incident light (ν1 > ν2). If the maximum value of kinetic energy of the photoelectrons emitted in the two cases are in the ration 1 : n then the threshold frequency of the metallic surface is ______.
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.
