Electrons

5.1  Electrons
 
  Thermionic emmision  
  The release of electrons from the heated metal surface.  
     
 
 

The factor that influences thermionic emission:

  1. The temperature of the cathode
    • As the temperature of the cathode increases, the rate of thermionic emission increases.
  2. The surface area of the cathode
    • As the surface area of ​​the cathode increases, the rate of thermionic emission increases.
  3. The potential difference between anode and cathode
    • As the potential difference between the anode and the cathode increases, the electron velocity increases, causing the electron beam to accelerate.
  4. The type of cathode
    • Made of tungsten.
  5. Cathode plating
    • Barium oxide, strontium oxide

      (lower the temperature for the beam)

 
 

The characteristics of cathode rays:

  1. Move-in a straight line at high velocity.
  2. Has momentum and kinetic energy.
  3. Kinetic energy \(\rightarrow\) light energy when an electron hits a fluorescent screen.

  4. Produces X-rays when exposed to heavy metals.

  5. Charged –ve.

  6. Can be deflected by magnetic field (Fleming left hand).

 
 

 

Electrons

5.1  Electrons
 
  Thermionic emmision  
  The release of electrons from the heated metal surface.  
     
 
 

The factor that influences thermionic emission:

  1. The temperature of the cathode
    • As the temperature of the cathode increases, the rate of thermionic emission increases.
  2. The surface area of the cathode
    • As the surface area of ​​the cathode increases, the rate of thermionic emission increases.
  3. The potential difference between anode and cathode
    • As the potential difference between the anode and the cathode increases, the electron velocity increases, causing the electron beam to accelerate.
  4. The type of cathode
    • Made of tungsten.
  5. Cathode plating
    • Barium oxide, strontium oxide

      (lower the temperature for the beam)

 
 

The characteristics of cathode rays:

  1. Move-in a straight line at high velocity.
  2. Has momentum and kinetic energy.
  3. Kinetic energy \(\rightarrow\) light energy when an electron hits a fluorescent screen.

  4. Produces X-rays when exposed to heavy metals.

  5. Charged –ve.

  6. Can be deflected by magnetic field (Fleming left hand).