Question

Two bulbs are reled `(P_(1),V)" and "(P_(2), V)`. If they are connected (i) iin series and (ii) in perallel across a supply V, find th power dissipated in the two combinations in terms of `P_(1)" and " P_(2)`.

Answer 1

`"Resistance of first bulb "rArrR_(1)=V^(2)/P^(1)`
`"Resistance of second bulb "rArrR_(2)=V^(2)/P^(2)`
When the two bulbs are connected inseries
`R_(s)=T_(1)+R_(2)`
`P_(s)=V^(2)/R^(s)=V^(2)/(R_(1)+R_(2))=V^(2)/(V^(2)/P^(1)+V^(2)/P^(2))" "rArrP_(s)=(P_(1)P_(2))/(P_(1)+P_(2))`
when the bulbs are connected in parallel

`1/R_(P)=1/R_(1)+1/R_(2)`
`1/R_(P)=P_(1)/V_(1)+P_(2)/V_(2)`
`P_(P)=V^(2)/R_(P)=V^(2)(P_(1)/V^(2)+P_(2)/V^(2))`