Question

Three wires of the same material are connected in parallel to a source of emf. Their lengths are in the ratio $1:2:3$ and cross-sectional areas are in the ratio $2:4:1$. Then, the ratio of power dissipated across them will be

Answer 1

Resistance$=\frac{\rho l}{A}$

Ratio of the resistances are $\frac{1}{2}:\frac{2}{4}:\frac{3}{1}$

$=1:1:6$

Power dissipated is in inverse relation to the resistance

Hence the ratio of power dissipated across them will be $6:6:1$