Sir, what is the difference between the formulas P=(I*I)R and P=(V*V)/R? On what context do we use the two?….A question by Rajit Roy.
This is a very good question and I thought of sharing the answer with you all.
The relation I^2R implies P proportional to R and is used when I is constant e.g. in a series combination of resistances I is same thro’ all the resistances.
V^2/R is used in a parallel combination of resistances. In this case V is constant and hence power is inversely related to R.
P.S. :Use I^2 R for power loss in transmission.