The filament of an electric lamp draws a current of $\displaystyle 0 \cdot 5 \mathrm{~A}$, which lights for $\displaystyle 2$ hours. Calculate the charge that flows through the circuit.

\[\begin{gathered} \mathrm{I}=0 \cdot 5 \mathrm{~A}, \mathrm{t}=2 \text { hours }=2 \times 3600 \mathrm{~s} \\ \mathrm{I}=\mathrm{Q} / \mathrm{t} \end{gathered} \] \(\displaystyle \therefore \mathrm{Q}=\mathrm{I} \times \mathrm{t}=0 \cdot 5 \mathrm{~A} \times 2 \times 3600 \mathrm{~s}=3600 \mathrm{C}\)