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A radioactive substance is placed in a lead block. The radiations coming out are subjected to an electrostatic field. One type of radiations move towards negative plate, a second type moves towards positive plate and the third remains unaffected. Similarly when the radiations are subjected to magnetic field in a direction perpendicular to their direction of motion alpha particles moves one side, beta particle moves to the other side and gamma rays remains unaffected. This clearly shows that there are three types of radioactive radiations 1) alpha, 2) beta and 3) gamma.
Properties:
1. Beta rays negatively charged particle each having a mass and a charge equal to that of an electron.
2. Beta rays are deflected by electric and magnetic fields.The deflection shows that they are negatively charged particles.
3. They affect photographic plates and cause fluorescence in various materials.
4. They produce less ionisation than alpha particles.
5. The penetrating power of Beta rays are greater than of Alpha rays.Beta rays can pass through a card board but it is stopped by an thin sheet of aluminium.
6. Beta rays move with velocities, sometimes upto 99% of the velocity of light.