Question

Same mass of copper is drawn into 2 wires of 1 mm thick ad 3 mm thick. Two wires are connected in series and current is passed. Heat produced in the wires is the ratio of
A. `3:1`
B. `9:1`
C. `81:1`
D. `1:81`

Answer 1

Correct Answer - C
`Q=i^(2)Rt`
`QalphaRalpha(1)/(A^(2))` when wire is stretched
`(Q_(1))/(Q_(2))=(r_(2)^(4))/(r_(1)^(4))=(3^(4))/(1^(4))=81.1`