Question

Two resistances , connected in parallel across a source of negligible interna resistance, consumes four times the power that they would consume when connected in series across the same source. If one of the resistances is `10 Omega` the other is
A. `5 Omega`
B. `10 Omega`
C. `20 Omega`
D. `40 Omega`

Answer 1

Correct Answer - B

`P_(1) = 4 P_(2)`
`(V^2)/(R_1R_2//(R_(1)+R_(2))) = 4*(V^2)/((R_1+R_2))`
`(R_(1)+R_(2))^(2) - 4R_(1)R_(2) = 0 implies (R_(1)-R_(2))^(2) = 0`
`R_(2) = R_(1) = 10 Omega`.