A transformer whose efficiency is 90%, draws 5 A when 200 V is applied to its primary coil. If output is drawn at 300 V, what is the current in secondary coil ? If number of turns in primary coil is 500, what is the number of turns in secondary coil?

Explanation

Here,`eta = 90%, I_(P) = 5 A, E_(P) = 200 V`
`I_(s) = ? E_(s) = 300 V, N_(P) = 500, N_(s) = ?`
As `eta = (E_(s) I_(s))/(E_(P) I_(P))`
`:. I_(s) = (eta E_(P) I_(P))/(E_(s)) = (90)/(100) xx (200 xx 5)/(300) = 3 A`
From `(E_(s))/(E_(P)) = (N_(s))/(N_(P))`
`N_(s) = (E_(s))/(E_(P)) xx N_(P) = (300)/(200) xx 500 = 750`