00:01
Here to solve this problem we use this following formula.
00:03
We know resistance of a wire is given by row l over a.
00:09
Here row is the resistivity of wire, l is the length of wire and a is the cross -sectional area of the wire.
00:15
For a circular cross -sectional, a is equal to pi r square.
00:22
Here r is the radius of the wire.
00:24
From this we obtain r is equal to row l or pi.
00:27
We know radius is equal to diameter over 2.
00:31
From this we obtain resistance r is equal to 4 row l over pi d square.
00:42
Suppose this is the equation number 1.
00:45
Now in this question a wire is given and resistivity of this wire is equal to row and we assume that the length of this wire is equal to l and diameter of this wire is equal to d.
00:57
Then in this condition the resistance of this wire is given by r is equal to 4 row l over pi d square.
01:03
Now we replace this wire by another wire...