Question

Two copper wires have their masses in the ratio 2 : 3 and lengths in the ratio, 3 : 4. Then the ratio of their resistances is

Answer 1

resistance is directly proportional to m*l

so

r1/r2=m1*l1/m2*l2

2*3/3*4

==1/2

Answer 2

Explanation:

R1/R2={l1/l2}^2×M2/M1

so = {3l1/4l2}^2×2M2/3M1

= 9/4 × 2/3 {m and l cancelled}

=18/12

=3/2

=3:2