Advertisements
Advertisements
प्रश्न
The wavelength λe of an electron and λp of a photon of same energy E are related by ______.
पर्याय
λp ∝ λe
`λ_p ∝ sqrt(lambda_e)`
`λ_p ∝ 1/sqrt(lambda_e)`
`λ_p ∝ lambda_e^2`
Advertisements
उत्तर
The wavelength λe of an electron and λp of a photon of same energy E are related by `bbunderline(lambda_p prop lambda_e^2)`.
संबंधित प्रश्न
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?
An isolated metal sphere is heated to a high temperature. Will it become positively charged due to thermionic emission?
Let i0 be the thermionic current from a metal surface when the absolute temperature of the surface is T0. The temperature is slowly increased and the thermionic current is measured as a function of temperature. Which of the following plots may represent the variation in (i/i0) against (T/T0)?
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.
Why do metals have a large number of free electrons?
Define the work function of a metal. Give its unit.
A 150 W lamp emits light of the mean wavelength of 5500 Å. If the efficiency is 12%, find out the number of photons emitted by the lamp in one second.
Consider Figure for photoemission.
How would you reconcile with momentum conservation? Note light (photons) have momentum in a different direction than the emitted electrons.
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.
