In β - emission from a radioactive substance an electron is ejected. This electron comes from
outer most orbit of atom
inner orbits of atom
the surface of substances
the nucleus of atom
Which of the following radiations suffers maximum deflection in magnetic field?
α - particles
β - particle
x - rays
γ - radiations
The diagram shows the paths of three different types of radiation, X, Y and Z.
X-Beta particles , Y - Alpha particles, Z = gamma particles
X-Gamma particles , Y - Alpha particles, Z = Beta particles
X-Beta particles , Y - Gamma particles, Z =Alpha particles
X-Alpha particles , Y - Beta particles, Z = gamma particles
Which of the following is most harmful for the human being :
Light rays
Beta particles
Gamma rays
Alpha particles
Which of the following is not a type of 'electron emission' from a metal surface?
Primary Emission
Secondary emission
Thermionic emission
Field emission
Why is graphite coating made on the inner side of the cathode ray tube ?
To change the brightness pattern on screen
To avoid the effect of external electric field on the beam of electrons
To avoid collisions of electrons with the air molecules
To produce fluorescence on the screen
The rate of emission of electrons from a surface does not depend upon:
the temperature of surface
the shape of metal surface
the nature of the metal surface
the surface area of metal
A radioactive substance emits radiations
α , β and γ simultaneously
In the order α, β and γ one by one
at one time α and β and then γ
α and γ , or β and γ
The atoms of the same element which have the same atomic number Z, but differ in their mass number is called
Isotopes
Isotones
Isobars
Nucleons
The total number of nucleons in the nucleus are called:
mass number
atomic number
Number of neutrons
None of these
