CBSE NOTES CLASS 12 PHYSICS
CHAPTER 11 DUAL NATURE OF RADIATION AND MATTER
Properties of cathode rays
- Cathode rays are not electromagnetic rays.
- Cathode rays are deflected by electric field and magnetic field.
- Cathode rays produce heat when they fall on the metals.
- Cathode rays can pass through thin aluminium or gold foils without puncturing them.
- Cathode rays can produce physical and chemical change.
- Cathode ray travel in straight line with high velocity, momentum and energy and cast shadow of objects placed in their path.
- On striking the target of high atomic weight and high melting point, they produce X-rays.
- Cathode rays produce fluorescence and phosphorescence in certain substance and hence affect photographic plate.
- When any charged particle move in a field where magnetic and electric fields are present, without any deviation, then Magnetic force = Electrostatic force
- Specific charge of cathode rays means the ratio of charge and mass. Specific charge of electron
E = electric field,
B = magnetic field and
V = potential difference applied across ends of tube.
Charge on electron e = -1.602 × 10-19 C.