For a battery the electromotive force is 1.5 V . Terminal voltage is 1.25 V . Power supplied to external resistance is 2.5 W . Find the internal resistance of battery.

Step-by-step solution

EMF of battery, E =1.5 ~V Terminal voltage, V =1.25 ~V Power supplied to external resistance (R), i.e. aligned P & =2.5 ~W P & = V ^2 R 2.5 & = (1.25)^2 R aligned array ll & R = 1.25 1.25 2.5 & R =0.625 array When battery is used to supply the power to load resistance, then V = E - Ir aligned V & =E- ( V R ) r r= ( E V -1 ) R= ( 1.5 1.25 -1 ) 0.625 & =0.125 aligned