Advertisements
Advertisements
प्रश्न
Why is a cathode ray tube evacuated to a low pressure?
Advertisements
उत्तर
The cathode ray tube is evacuated to a low pressure to avoid collisions of electrons with air molecules.
APPEARS IN
संबंधित प्रश्न
Name the radiations which are absorbed by greenhouse gases in the earth’s atmosphere.
How can they be made to leave the metal surface? (State any two ways)
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.
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 ?
Give a scientific explanation.
When the radiation coming out from a certain radioactive substance is passed through an electric field, marks are found at three places on the photographic plate placed in its path.
An element P disintegrates by α - -emission and the new element suffers two further disintegrations, both by β -emission, to form an element Q. Explain the fact that P and Q are the isotopes.
Define free electrons.
What do you mean by electron emission?
State three ways of obtaining an electron-beam.
The half-life of a radioactive nuclide is 100 hours. The fraction of original activity that will remain after 150 hours would be ______.
