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प्रश्न
In a cathode ray tube state:
(i) the purpose of covering cathode by thorium and carbon.
(ii) the purpose of the fluorescent screen.
(iii) how is it possible to increase the rate of emission of electrons.
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उत्तर
(i) The cathode is covered with thorium and carbon as it has low work function and it needs to be heated up to 2000 K to emit electrons. This serves it as a better electron emitter than tungsten.
(ii) The fluorescent screen helps in changing the electrical signal applied on the deflecting plates into the visual pattern on the screen.
(iii) The rate of emission of the electrons can be increased by
- Using a metal with a lower work function,
- Increasing the temperature of the surface of the metal, or
- Increasing the surface area of the metal emitting the electrons.
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संबंधित प्रश्न
Answer the following questions based on a hot cathode ray tube.
What will happen to the beam when it passes through the electric field?
Represent the change in the nucleus of a radioactive element when a β particle is emitted.
State any two precautions to be taken while handling radioactive substances
A nucleus `""_11^24Na` emits a beta particle to change into Magnesium (Mg)
(i) Write the symbolic equation for the process.
(ii) What are numbers 24 and 11 called?
(iii) What is the general name of `""_12^24Mg `with respect to `""_11^24Na` ?
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.
Justify with reason, whether the following nuclear reactions are allowed or not.
\[\ce{^A_Z X -> ^A_{Z + 1}Y + ^0_{-1}β}\]
From α, β and γ-rays, name the one which travels with the speed of light?
State one use of radio-isotopes.
The count rate of activity of a radioactive sample of a very large population decreased from 1024 to 128 in 3 minutes. Then the rate of disintegration at the end of 5 minutes is ______.
