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प्रश्न
Why are materials of low work function preferred as thermionic cathode materials?
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उत्तर
By using materials of low work functions, the emission of electrons from such a surface takes place at relatively low temperature (at 1700°C in instead of 2500°C approximately).
संबंधित प्रश्न
A radioactive substance is oxidized. Will there be any change in the nature its radioactivity? Give a reason for your answer
Name a gas caused by the Greenhouse effect
What are isobars?
What do you mean by Mass number.
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?
What is nucleus of an atom? Compare its size with that of the atom. Name its constitutents. How is the number of these constituents determined by the atomic number its atomic model.
Two radioactive nuclei are represented by xAp and yAq and when p and q are mass numbers and x, y are the atomic number. How can the products be represented, i .e., what are the new values of p, q. x and y after the emission of an α-particle and a β-particle from A and B respectively.
From α, β and γ-rays, name the one which is not affected by electric or magnetic field?
In the following atoms, which one is a radioisotope? Give one use of this isotope.
O16, C14, N14, He4
Assertion (A): The force of repulsion between atomic nucleus and α-particle varies with distance according to inverse square law.
Reason (R): Rutherford did α-particles scattering experiment.
