Physics - Current Electricity Question with Solution | TestHub

Power of battery, when charged is given by ${\mathrm{P}}_1={\mathrm{V}}_1{\mathrm{I}}_1$ Electrical energy dissipated id given by $\begin{array}{l}{\mathrm{E}}_1={\mathrm{P}}_1{\mathrm{t}}_1\\ {\mathrm{E}}_1={\mathrm{V}}_1{\mathrm{I}}_1{\mathrm{t}}_1=15\times 10\times 8=1200\mathrm{Wh}\end{array}$ Similarly, the electrical energy dissipated during the discharge of battery is given by $\begin{array}{l}{\mathrm{E}}_2={\mathrm{V}}_2{\mathrm{I}}_2{\mathrm{t}}_2\\ =14\times 5\times 15=1050\mathrm{Wh}\end{array}$ Hence, watt-hour efficiency of the battery $\Rightarrow \eta =\frac{E_2}{E_1}\times 1000.875\times 100=87.5\%$