SSE JE Electrical Engineering 24 March 2021 Shift 1 Paper

The magnitude of net emf of an ideal transformer is given by the formula:
$\mathrm{E}=4.44\times \mathrm{f}\times \mathrm{N}\times {\mathrm{\varphi }}_{\mathrm{m}}$
Where E = RMS value of applied voltage.
f = frequency of the transformer.
N = number of turns.
${\mathrm{\varphi }}_{\mathrm{m}}$ = the magnitude of maximum flux in the core.
$\mathrm{E}=111\mathrm{V},\mathrm{f}=50\mathrm{Hz},\mathrm{N}=200$
$111=4.44\times 50\times 200\times {\mathrm{\varphi }}_{\mathrm{m}}$
${\mathrm{\varphi }}_{\mathrm{m}}=\frac{111}{\left(4.44\times 50\times 200\right)}$$=2.5\mathrm{mWb}$