Question

A power transmission line feeds input power at 2300v to a step down transformer with its primary windings having 4000 turns giving the output power at 230v. If the current in the primary of the transformer is 5a and its efficiency is 90% the output current would be

Answer 1

we know, formula, $\eta=\frac{P_s}{P_p}$
where, $\eta$ is efficiency , $P_s$ denotes pawer of secondary transmission, $P_p$denotes power of primary transmission.

given, $\eta$ = 90% = 0.9
$P_s=V_s\times I_s$ = 230v × $I_s$
$P_p=V_p\times I_p$ = 2300 × 5

so, 0.9 = 230 × $I_s$/2300 × 5

hence, $I_s$ = 45A

therefore, output current would be 45A.