Question

A transformer has 500 turns in its primary and 1000 turns in its secondary winding.The primary voltage is 200 V and the load in the secondary is 100 ohm.Calculate the current in the primary,assuming it to be a ideal transformer.

• A. 25 A
• B. 45 A
• C. 8A
• D. 22 A

Answer 1

The correct option is C 8A

In usual rotation we have -

$\Rightarrow \frac{V_s}{V_p}=\frac{N_s}{N_p}$

$\therefore V_S=V_p\times \frac{N_s}{N_p}$

$=200v\times \frac{1000}{500}$

$=400V$

There is load resistance of $100\Omega$ in the secondary circuit. Therefore current in the secondary

$\Rightarrow i_s=\frac{V_s}{R_s}=\frac{400V}{100\Omega }=4A$

In an ideal transformer the output power and input power are equal that is

$\Rightarrow V_s\times i_s=V_p\times i_p$

$\therefore i_p=i_s\times \frac{V_s}{V_p}=4A\times \frac{400V}{200V}$

$=4A\times 2$

$=8A$

Hence, the answer is $8A.$