Figure shows an iron-cored transformer assumed to be 100% efficient. The ratio of the secondaty turns to the primary turns is 1:20.

A 240 V ac supply is connected to the primary coil and a `6 Omega` resistor is connected to the secondary coil. What is the current in the primary coil?

Options

A. 0.10A
B. 0.14A
C. 2A
D. 40A

Answer

A

Explanation

the equivlent primary load is
`(R_1)=((N_1)/(N_2))^(2) (R_2)=((20)/(1)^(2)) (6.0)=2400 Omega`
Current in the primary coil
`=(240)/(R_1) =(240)/(2400)=0.1 A`