A step-up transformer has the turns in the ratio of 1:20. A resistance of 100Ω connected across the secondary is drawing a current of 2A. The primary voltage and the current, respectively, are

Question

A step-up transformer has the turns in the ratio of 1:20. A resistance of 100Ω connected across the secondary is drawing a current of 2A. The primary voltage and the current, respectively, are (A) 100V,0.5A (B) 200V,10A (C) 10V,40A (D) 10V,20A

Tardigrade Admin · Accepted Answer

For ideal transformer (N2/N1)=(E2/E1)=(i1/i2)⇒ (20/1)=(i1/2) ⇒ i1=40A and E1=200× (1/20)=10V

Q. A step-up transformer has the turns in the ratio of $1 : 20.$ A resistance of $100Ω$ connected across the secondary is drawing a current of $2 A .$ The primary voltage and the current, respectively, are

$100 V, 0.5 A$

$200 V, 10 A$

$10 V, 40 A$

$10 V, 20 A$

For ideal transformer
$\frac{N _{2}}{N _{1}} = \frac{E _{2}}{E _{1}} = \frac{i _{1}}{i _{2}} \Rightarrow \frac{20}{1} = \frac{i _{1}}{2}$
$\Rightarrow i_{1} = 40 A$ and $E_{1} = 200 \times \frac{1}{20} = 10 V$

Q. A step-up transformer has the turns in the ratio of 1:20. A resistance of 100Ω connected across the secondary is drawing a current of 2A. The primary voltage and the current, respectively, are

100V,0.5A

200V,10A

10V,40A

10V,20A