# Electrical Engineering - Transformers

### Exercise :: Transformers - General Questions

6.

The primary winding of a transformer has 110 V ac across it. What is the secondary voltage if the turns ratio is 8?

 A. 8.8 V B. 88 V C. 880 V D. 8,800 V

Explanation:

V2/V1 = N2/N1

Turns ratio = N2/N1 = 8.

V2/110 = 8

V2 = 8 x 110

V2 = 880v.

7.

To step 110 V ac down to 20 V ac, the turns ratio must be

 A. 5.5 B. 18 C. 0.18 D. 0.018

Explanation:

Vp/Vs = Np/Ns

Vs = (Ns/Np)Vp

We required turns ratio i.e., (Ns/Np)

= Vs/Vp

= 20/110

= 0.181818182

[Note: p - primary; s - secondary]

For step down transfer, the turns ratio will be less than 1.

For simulation: Step-Down Transformer Circuit Simulator.

8.

The mutual inductance when k = 0.65, L1 = 2 H, and L2 = 5 H is

 A. 2 mH B. 2 H C. 4 H D. 8 H

Explanation:

No answer description available for this question. Let us discuss.

9.

If 25 W of power are applied to the primary of an ideal transformer with a turns ratio of 10, the power delivered to the secondary load is

 A. 25 W B. 0 W C. 250 W D. 2.5 W

Explanation:

No answer description available for this question. Let us discuss.

10.

A transformer with a 110 V primary has a 15:1 turns ratio. The load resistance, RL, is 120 . What is the approximate voltage across the load?

 A. 7.3 V B. 73 V C. 88 V D. 880 V