Question

If the resistance doubles while the voltage stays the same, what effect will that have on the power?
A.It will increase by a factor of 2.
B.It will decrease by a factor of 2.
C.It will increase by a factor of 4.
D.It will decrease by a factor of 4.

Answer 1

The best formula to use for this question is

             Power = (voltage)² / R

So      Original power = (voltage)² / (original R)
and
           New power  =  (same voltage)² / (2 x original R)

That's equal to            (1/2) (voltage)² / (original R)

which is equal to    (1/2) (original power) .

So I guess the power decreases by half, and that's choice-B .