- has negative charge and its mass is equal to that of an electron.
- All emitted from a substance have big range of velocities anywhere from 0.3c to 0.9c where c is the speed of light. Note that, at high velocities e/m decreases indicating the increase in mass of the particle according to Einstein’s equation
- They have low ionizing power so they cover large range.
- They can affect photographic plate.
- They can produce fluorescence in willemite, barium platinocyanide etc.
- They are deflected by magnetic and electric field. Their direction of deflection has proven that they are negatively charged particles.
- can penetrate through thin metal foils and their penetration power is higher that that of
- The value of e/m for beta rays was proved to be the same as that of cathode rays. The charge on a was observed to be the same as the charge of an electron. Therefore are identical with electrons.