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प्रश्न
State two characteristics of the substance used as thermionic emitter.
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उत्तर
(i) The substance must have high melting point.
(ii) The work function of the substance should be low so that electrons may be emitted even at low temperature.
संबंधित प्रश्न
An electromagnetic radiation is used for photography in fog. [2]
(i) Identify the radiation.
(ii) Why is this radiation mentioned by you, ideal for this purpose ?
When is said to be the nucleus unstable?
A radioactive source emits three types of radiations. Name them.
(i) Name the radiations which are charged.
(ii) Name the radiations which are most penetrating.
(iii) Name the radiations which travel with the speed of light.
(iv) Name the radiations which have the largest mass.
In the following fig. shows a radioactive source S in a thick lead container. The radiations pass through an electric field between the plates P and Q. Complete the diagram to show the paths of α , β and γ radiations.
Why is the source S placed in a thick lead container?
During the emission of a beta particle, the ______ number remains same.
Define bound electrons.
How is a zinc sulphide screen affected when a cathode ray beam strikes it?
What is meant by Radioactivity?
State three common properties of beta rays and cathode rays.
