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

Answer: Option C

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

Answer: Option C

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

Answer: Option B

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

Answer: Option A

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

Answer: Option A

Explanation:

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