Advertisements
Advertisements
प्रश्न
State two properties that a substance should possess when used as a thermionic emitter.
Advertisements
उत्तर
Two properties are:
(i) High melting point. (ii) Low work function.
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)
Define the term radioactivity.
Draw a diagram of a simple atom showing the nucleus and electrons. In this atom:
(a) What type of charge will there be on the nucleus?
(b) What is the value of this charge?
Why should a radioactive substance not be touched by hands?
State three ways of obtaining an electron-beam.
A radioactive nucleus \[\ce{^A_ZX}\] undergoes spontaneous decay in the sequence \[\ce{^A_ZX -> _{Z-1 }B -> _{Z-3}C -> _{Z-2}D }\], where Z is the atomic number of element X. The possible decay particles in the sequence are ______.
A radioactive element is placed in an evacuated chamber. Then the rate of radioactive decay will ______.
In the following atoms, which one is a radioisotope? Give one use of this isotope.
O16, C14, N14, He4
