Advertisements
Advertisements
प्रश्न
How can they be made to leave the metal surface? (State any two ways)
Advertisements
उत्तर
Electron emission from the metal surface can be (any two):
1) Thermionic emission – when energy is supplied as heat
2) Photoelectric emission – when energy is supplied as energy.
3) Field emission – when energy is supplied by applying an electric field to accelerate the electrons.
4) Secondary emission – when energy is supplied from the kinetic energy of other electrons on collisions with them.
APPEARS IN
संबंधित प्रश्न
Why is a cathode ray tube evacuated to a low pressure?
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` ?
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 ?
In following fig. shows a mixed source S of alpha and beta particles in a thick lead container. The particles pass through a magnetic field in a direction perpendicular to the plane of paper (inwards as shown by x). State and show in the diagram how the particles get affected.
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?
State three safety precautions that you would take while handling the radioactive substances.
What are the types of emission?
State two properties that a substance should possess when used as a thermionic emitter.
What is meant by Radioactivity?
Are all the radiations viz. α, β and γ emitted in a single radioactive decay?
