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प्रश्न
What do you mean by electron emission?
उत्तर
Free electrons leave the metal surface only if sufficient energy is supplied to the metal. This emission of electrons from metal surface is called the electron emission.
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संबंधित प्रश्न
What is meant by radioactivity?
What kind of change takes place in a nucleus when a β -particle is emitted?
Radioactive substances were found to give off three types of rays. Name them. How do they
(a) React to the magnetic field?
(b) React to the electric field?
(c) Act when different thickness of lead sheets is placed in their path?
State two properties that a substance should possess when used as a thermionic emitter.
How is a cathode ray beam affected while passing through an electric field?
State any two uses of cathode rays.
The half-life of a radioactive nuclide is 100 hours. The fraction of original activity that will remain after 150 hours would be ______.
If 10% of a radioactive substance decays in every 5 years, then the percentage of the substance that will have decayed in 20 years will be ______.
A radioctive sample decays `7/8` times its original quantity in 15 minutes. The half-life of the sample is ______.
