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

Answer:

Explanation:

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

$P=\frac{V^2}{R}$  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 $P=\frac{V^2}{R}$ 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