Electricity module

Electricity module

1. Kirchoff's Laws

   • 1st: The sum of current going into a junction must equal the sum of current exiting that junction.
   • 2nd: The sum of P.D. must equal the sum of E.M.F.

2. Resistance

   • = Resistivity x length/ Cross sectional area
   • As temperature of metal increases, the amplitude of the lattice ions vibrations increase so the electrons tend to collide with the lattice ions more often. This reduces the mean drift velocity and as a result the current.

3. Drift velocity

   • I=nAve
   • The average velocity at which electrons move along a conductor towards the positive terminal

4. Voltage

   • E=V+Ir
   • P.d.=Work Done/Charge
   • 1W= 1Js ^-1