Transformer — Practice Quiz

Question 1

A transformer has N_p = 200, N_s = 1000. Primary fed with 50 V AC. Secondary voltage:

Accepted Answer

250 V

Answer

10 V

Answer

100 V

Answer

1000 V

Question 2

Same transformer. If primary current is 5 A, secondary current is:

Accepted Answer

1 A

Answer

25 A

Answer

0.5 A

Answer

10 A

Question 3

A transformer cannot work on DC because:

Accepted Answer

DC produces no changing flux

Answer

DC is too high voltage

Answer

DC is too dangerous

Answer

Transformers need 3-phase

Question 4

Why is electrical power transmitted at very high voltages?

Accepted Answer

To reduce I²R line losses (lower I for same P)

Answer

To prevent shocks

Answer

Higher V is cheaper to generate

Answer

Transformers prefer high voltage

Question 5

Ideal transformer efficiency is:

Accepted Answer

100%

Answer

50%

Answer

75%

Answer

90%