WHY MY ANS IS WRONG?

Asked by  | 20th Feb, 2010, 11:17: AM

Expert Answer:

Let's find the answer by a simple experiment.

Pick a battery of potential 10V, we'll connect it across a resistor of 10 Ω.

The current will be 1 A. and Power = VI = 10 W = V2/R = 100/10 = 10 W = I2R = (12)(10) = 10 W

Now if we want to see how the power is affect as we change the resistance, we have to keep increasing or decreasing the resistance, with contant potential.

Let's increase the resistance to 20 Ω.

V = 10 V, I = 0.5 A and Power = VI = 5 W = I2R = (0.52)(20) = 5 W = V2/R = 100/20 = 5 W.

So as we keep on increasing the R value we find the power is decreasing. And since the two equations, P = V2/R = I2R are equivalent, but not independent, they are related by Ohm's Law.

Regards,

Team,

TopperLearning.

Answered by  | 20th Feb, 2010, 12:41: PM

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