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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
Write one use of cathode ray tube.
Why is a cathode ray tube evacuated to a low pressure?
Name a gas caused by the Greenhouse effect
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(a) What type of charge will there be on the nucleus?
(b) What is the value of this charge?
A radioactive nucleus `""_"Z"^"A"` X first emits a beta particle and then an alpha particle to give the resulting nucleus `""_"Q"^"P"` Y What will be the values of P and Q in terms of A and Z?
How is a cathode ray beam affected while passing through a magnetic field?
The mean lives of a radioactive substance are 1620 and 405 years for β-emission and β-emission respectively. The time after which three fourth of a sample will decay if it is decaying both by β-emission and β-emission simultaneously will be ______ years.
(Take ln 2 = 0.693)
When an α-particle of mass m moving with velocity ν bombards on a heavy nucleus of charge Ze, its distance of closest approach from the nucleus depends on m as:
