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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
Represent the change in the nucleus of a radioactive element when a β particle is emitted.
Radiations given out from a source when subjected to an electric field in a direction perpendicular to their path are shown below in the diagram. The arrows show the path of the radiation A, B and C. Answer the following questions in terms of A, B and C.
1) Name the radiation B which is unaffected by the electrostatic field.
2) Why does the radiation C deflect more than A?
3) Which among the three causes the least biological damage externally.
4) Name the radiation which is used in carbon dating.
State three safety precautions that you would take while handling the radioactive substances.
State any two uses of cathode rays.
In a cathode ray tube state the purpose of covering cathode by thorium and carbon.
A certain nucleus has a mass number 20 and atomic number 9. Find the number of neutrons and protons present in it.
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.
Mention four properties of Becquerel rays.
The half-life of a radioactive nuclide is 100 hours. The fraction of original activity that will remain after 150 hours would be ______.
