A step down transformer converts a voltage of 2200 V into 220 V in the transmission line. Number of turns in primary coil is 5000. Efficiency of transformer is 90% and its output power is 8kW. Calculate (i) number of turns in secondary coil (ii) input power.

Explanation

`"Efficiency "eta=("Output power")/("Input power")`
`"or Input power"=("Output power")/(eta)=(8)/(90//100)=8.9kW`
`"Again "(N_(s))/(N_(p))=(E_(s))/(E_(p)) or N_(s)=(E_(s))/(E_(p))xxN_(p)`
`"Here "N_(p)=5000,E_(s)=220V, E_(p)=2200V`
`therefore N_(s)="500 turns"`