Question

The power dissipated in a resistor is given by P = V 2 / R , which means power decreases if resistance increases. Yet this power is also given by P = I 2R , which means power increases if resistance increases. Explain why there is no contradiction here?

Answer 1

Step-by-step explanation:

Power Dissipated in a resistor is given by two methods i.e.

`P=(V^2)/(R)` and

`P=I^2\cdot R`

where
`V=Potential\ difference`

`R=resistor`

`I=current`

both formula gives Power but Former is used when voltage is constant i.e. when resistors are in parallel and the later is used when the resistor are in series .

Though
`P=(V^2)/(R)` can also be used in series but we have to calculate the Potential drop across each resistor then we can apply the formula.

Similar is with
`P=I^2R`

First we have to calculate current through each resistor then we can apply the Formula