A step-down transformer with an efficiency of 80% is used on a 1000 V line to deliver 10 A at 100 V at the secondary coil. The current drawn from the line is

Options

A. `1.5` A
B. 2A
C. `3A`
D. `1.25A`

Answer

D

Explanation

Given, `eta = 80%, V_("In") = 1000 V, I = 10A and V= 100V`
Output power
`P_("out") = Ixx V`
`P_("out") = 10 xx 100`
`P_("out") = 1000 VA`
and `P_("in") = (P_("in"))/(V_("in")) = (1000)/(0.8 xx 1000)`
`I_("in") = 1.25 A`