1. They are a stream of fast-moving electrons. Each electron carries a negative charge of 1.6 * 10-19 C and has a mass of 1/1840 amu (atomic mass unit, 1 amu = mass of proton or neutron).
2. They process considerable kinetic energy.
3. They produce a heating effect on striking a metal target.
4. They can be deflected by magnetic and electrostatic fields.