Advertisements
Advertisements
प्रश्न
Give an example each of a metal from which photoelectric emission takes place when irradiated by
- UV light
- visible light.
Advertisements
उत्तर
- Photoelectric emission takes place when Zn is irradiated with UV radiation.
- Photoelectric emission takes place when Na is irradiated with visible light.
APPEARS IN
संबंधित प्रश्न
Quarks inside protons and neutrons are thought to carry fractional charges [(+2/3)e; (–1/3)e]. Why do they not show up in Millikan’s oil-drop experiment?
An isolated metal sphere is heated to a high temperature. Will it become positively charged due to thermionic emission?
The cathode of a diode valve is replaced by another cathode of double the surface area. Keeping the voltage and temperature conditions the same, will the place current decrease, increase or remain the same?
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.
Define the term "Threshold frequency", in the context of photoelectric emission.
The work function of aluminum is 4⋅2 eV. If two photons each of energy 2⋅5 eV are incident on its surface, will the emission of electrons take place? Justify your answer.
The wavelength λe of an electron and λp of a photon of same energy E are related by ______.
Define the work function of a metal. Give its unit.
In which case is electron emission from a metal not known?
Name the factors on which photoelectric emission from a surface depends.
