Two resistance `R_(1) and R_(2)` may be connected either in series or in parallel across a battery of zero internal resistance. It is required that the joule heating for the parallel combination be five times that for series combination if `R_(1)` is `100 Omega` find `R_(2)`.

Answer

`261.8 Omega or 38.2 Omega`

Explanation

As perquestion
`(V^(2))/(R_(1)R_(2)//(R_(1) + R_(2))) = 5 xx (V^(2))/((R_(1) + R_(2)))`
or ` (R_(1) + R_(2))^(2) = 5R_(1)R_(2) pot R_(1) = 100 Omega `
and solve at for `R_(2)`