Question

(iv) if the radius of the conductor is doubled, the ratio of its new
resistivity to the old pne is​

Answer 1

Answer:

The ratio will be 4:1

Explanation:

The resistance of a conductor repends inversely on the area of the cross section. That is greater the area of cross section, lesser is the resistance.

Here, we use πr² for area of cross section

Let r be the old radius, then

Area of cross section: πr²

Let the new radius be 2r, then

New area of cross section: π(2r)² = π4r²

The ratio of resistance:

π4r²/πr² (removing common terms)

4:1