Question

The resistance of a wire of length 250 m is 1 ohm. If the resistivity of the material of wire is 1.6 x 10–8 ohm meter, find the area of cross-section of the wire. How much does the resistance change if the diameter is doubled?

Answer 1

answer is given in the picture plz check and thanks for asking

Answer 2

hey bro/gal.

since, resistance = resistivity× length / area

=) 1 = 1.6 * 10^-8 * 250/ A

=) A = 400*10^-8 = 4*10^-6 m²

=) if diameter is doubled then area will become 4A.

=) new Area = A' = 4*4*10^-6 = 16*10^-6 m²

=) R' = 1.6*10^-8 * 250/ 16*10^-6

= 1/4 ohm.