Question

A house is served by 220 V supply line. In a circuit protected by a fuse marked by 9 amp, the maximum number of 60 W lamps in parallel that can be turned on is?

Answer 1

Dear Student,

$$\begin{gathered} \mathrm{We}\mathrm{know}\mathrm{that} \\ \mathrm{P}=\mathrm{VI} \\ \mathrm{where},\mathrm{P}=\mathrm{power}=60\mathrm{W} \\ \mathrm{V}=\mathrm{voltage}=220\mathrm{V} \\ \mathrm{I}=\mathrm{current}=9\mathrm{A} \\ \mathrm{Maximum}\mathrm{number}\mathrm{of}\mathrm{lamps}\mathrm{in}\mathrm{parallel}\mathrm{are}, \\ \mathrm{P}=\frac{\mathrm{VI}}{\mathrm{n}} \\ \mathrm{n}\times \mathrm{P}=\mathrm{VI} \\ \mathrm{n}\times 60=220\times 9 \\ \mathrm{n}=33 \end{gathered}$$