Voltage across primary \(V_{p}=220\, \mathrm{V}\)
Current in the primary \(I_{p}=0.5\, \mathrm{A}\)
Efficiency of a transformer \(\eta=\frac{\text { output power }}{\text { input power }} \times 100\)
\(=\frac{P}{V_{p} I_{p}} \times 100=\frac{100}{220 \times 0.5} \times 100\)
\(=90 \%\)
જ્યાં $l$ દરેક ટ્યુબની પહોળાય છે.