A transformer with efficiency 80% works at 4 kW and 100 V. If the secondary voltage is 200 V, then the primary and secondary currents are respectively

Question

A transformer with efficiency 80% works at 4 kW and 100 V. If the secondary voltage is 200 V, then the primary and secondary currents are respectively (A) 40 A and 16 A (B) 16 A and 40 A (C) 20 A and 40 A (D) 40 A and 20 A

Tardigrade Admin · Accepted Answer

Here, η = 80 % Pi = 4 kW = 4000 W Vp = 100 V, Vs = 200 V Ip=(pi/Vp)=(4000/100)=40 A η=(Vs Is/Vp Ip); (80/100)=(200Is/4000)=(Is/20) or Is=(20×80/100)=16 A

Q. A transformer with efficiency 80% works at $4 kW$ and $100 V$ . If the secondary voltage is $200 V$ , then the primary and secondary currents are respectively

40 A and 16 A

16 A and 40 A

20 A and 40 A

40 A and 20 A

Here, $η$ = 80 %
$P_{i}$ = 4 kW = 4000 W
$V_{p}$ = 100 V, Vs = 200 V
$I_{p} = \frac{p _{i}}{V _{p}} = \frac{4000}{100} = 40 A$
$η = \frac{V _{s} I _{s}}{V _{p} I _{p}}; \frac{80}{100} = \frac{200 I _{s}}{4000} = \frac{I _{s}}{20}$
or $I_{s} = \frac{20 \times 80}{100} = 16 A$

Q. A transformer with efficiency 80% works at 4kW and 100V. If the secondary voltage is 200V, then the primary and secondary currents are respectively