WAEC Physics 2018 Paper

The ideal transformer (either step-up or step-down) works with the equation:

$\;\frac{V_{s}}{V_{p}} = \;\frac{N_{s}}{N_{p}} = \;\frac{I_{p}}{I_{s}}$

where $V_{s}$ and $V_{p}$ are the voltages applied to the secondary and the primary respectively

$N_{s}$ and $N_{p}$ are the number of turns on the secondary and primary coils respectively

$I_{p}$ and $I_{s}$ are the currents flowing in the primary and secondary coils respectively.

$\;\frac{V_{s}}{100} = \;\frac{200}{100}$

$V_{s} = \;\frac{200 \times 100}{100} = 200V$