Question

two metallic wires A and B are connected in parallel. wires A has length L and radius R, wire B has a length 3 l and radius 3r. compute the ratio of total resistance of parallel combination and the resistance of wire A???
plz anwer this....​

Answer 1

Explanation:

Rp=Ra×Rb/Ra+Rb-----(1)

w.k.t R=rho×l/A

R=rho×l/pi×r^2

take rho/pi=k=constant

R=l/r^2

from (1)

Rp=(L/R^2)×(3l/9r^2) / (L/R^2)+(3l/9r^2)

Rp=L/R^2×l/3r^2 / L/R^2 +l/3r^2

Rp=L×l / 3Lr^2+lR^2------(2)

Ra=L/R^2

Rp/Ra=lR^2 / 3Lr^2 +lR^2