Question

Keeping the potential difference constant, the resistance of a circuit is halved. By how much does the current change?

Answer 1

From Ohm's law we have:
V/I = R
Or I = V/R
Now, according to the question, the resistance of the circuit is halved and the potential difference is constant.
i.e. R' = R/2
and V' = V
Then the new current is given by:
I' = V'/R'
= V/R/2
= 2V/R
= 2I

It is clear from the above statement that the current becomes double.