The input and output voltages of a transformer are 220 V and 44 V respectively. Find (a) the turns ratio (b) the current in input circuit if the output current is 2 A.

(a) Given,

E_p = 220 V

E_S = 44 V

Now,

$\dfrac{E$s}{Ep} = \dfrac{Ns}{Np}

Substituting the values in the formula we get,

$\dfrac{44}{220} = \dfrac{N$s}{Np} \\[0.5em] \Rightarrow \dfrac{Ns}{Np} = \dfrac{44}{220} \\[0.5em] \Rightarrow \dfrac{Ns}{Np} = \dfrac{1}{5} \\[0.5em]

Hence, turns ratio = 1 : 5

(b) I_s = 2 A

I_p = ?

From relation,

${E$s}{Is} = {Ep}{Ip}

Substituting the values in the formula we get,

$44 \times 2 = 220 \times I$p \\[0.5em] \Rightarrow Ip = \dfrac{44 \times 2}{220} \\[0.5em] \Rightarrow I_p = 0.4 A \\[0.5em]

Hence, input current = 0.4 A