Question

keeping the potential difference constant ,the resistance of the circuit is doubled.By how much does the current change?

Answer 1

As from Ohm's Law,
V = IR........1
Now, here V is constant.
Let , new resistance R' = 2R and assume that current flow be I'
So, from 1,
IR = I'.R',
-> IR = I'.2R,
Therefore, I' = I / 2

So the current is halved.

Answer 2

Answer:

According to ohm's law

R =v/I...............(1)    ( R=resistance, V=voltage , I =current )

let I' be the current when Resistance become double

2R = V/I'   ............(2)                           (V is constant)

dividing equation (2) by (1) 

R/2R= (V/I)/V/I'

1/2=I'/I

I=2I'

I/2=I'

Current through conductor become half