## Wednesday, September 14, 2011

### Proportionality relation in electric power

Power is directly proportional as well as inversely proportional by two formulae.How does one justify?
P=V2/R as well as p=I2 R.

This means that for a given current, (i.e, when current is kept constant) Power is directly proportional to resistance.

eg, when a number of appliances are connected in series, the same current passes though all and the power dissipated  in each will be directly proportional to their resistances.

For a given constant voltage, the power is inversely proportional to resistance.

For eg; when a number of appliances are connected in parallel across the same voltage, then the power dissipated in each is inversely proportional to their resistances.