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प्रश्न
How can they be made to leave the metal surface? (State any two ways)
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उत्तर
Electron emission from the metal surface can be (any two):
1) Thermionic emission – when energy is supplied as heat
2) Photoelectric emission – when energy is supplied as energy.
3) Field emission – when energy is supplied by applying an electric field to accelerate the electrons.
4) Secondary emission – when energy is supplied from the kinetic energy of other electrons on collisions with them.
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संबंधित प्रश्न
When does the nucleus of an atom tend to become radioactive?
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Why is the source S placed in a thick lead container?
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Why are materials of low work function preferred as thermionic cathode materials?
State one use of radio-isotopes.
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- α particles are photons
- Penetrating power of γ radiation is very low
- Ionization power is maximum for α rays
- Penetrating power of γ radiation is very high
The half-life of a radioactive nuclide is 100 hours. The fraction of original activity that will remain after 150 hours would be ______.
Two radioactive materials A and B have decay constants 25λ and 16λ respectively. If initially they have the same number of nuclei, then the ratio of the number of nuclei of B to that of A will be "e" after a time `1/("a"lambda)` The value of a ______.
