Physics

Problem

Two copper wires A and B are of equal length

1.5\,\text{m}

but have diameters

0.80\,\text{mm}

and

0.40\,\text{mm}

respectively. a. (i) Calculate the ratio of their cross-sectional areas

A_A : A_B

. b. (ii) Determine the ratio of their resistances

R_A : R_B

. c. (iii) If the resistance of wire A is measured to be

1.2\,\Omega

, find the resistance of wire B.