Transformer MCQs Part 3

Transformer MCQs Part 3. Multiple choice questions on Electric transformers with brief explanatory answers and solutions.

An ideal transformer is the one that has

An ideal transformer is the one that has:

1. Same number of primary and secondary turns
2. Same voltage per turns on primary and secondary side
3. Both of above
4. No losses and leakage resistance

Correct answer: 4. No losses and leakage resistance

Explanation:

An ideal transformer possesses following features:

1. It has no leakage flux
2. It has no core losses
3. It has no winding resistance

However, the real-life transformer has some losses, possess some windage resistance and has some leakage reactance as well.

The primary and secondary of a transformer are coupled

The primary and secondary of a transformer are coupled:

1. Magnetically
2. Electrically
3. Both of these
4. None of these

Correct answer: 1. Magnetically

Explanation: The electrical transformer is a device that changes AC electric power at one voltage level to AC electric power at another volt age level through the action of a magnetic fie ld. Its basic construction involves two or more coils of wire wrapped around a common ferromagnetic core. For power transformers these coils are (usually) not directly connected. The only connection between the coils is the common magnetic flux that is present within the core.

If a is defined as turns ratio of transformer and is equal to 5, then such a transformer will be

If a is defined as turns ratio of transformer and is equal to 5, then such a transformer will be:

1. Step up transformer
2. Step down transformer
3. Any of above
4. None of above

Correct answer: 2. Step down transformer

Explanation:

Turns ration (a) = Np/Ns = Vp/Vs

Suppose a = 5, and Vp = 2

Then Vs = 2/5 = 0.4

Since Vs < Vp, the transformer is a step down transformer.

Generally, a transformer transfers electrical energy from primary to secondary with a change in

Generally, a transformer transfers electrical energy from primary to secondary with a change in:

1. Frequency
2. Voltage
3. Power
4. Time period

Correct answer: 2. Voltage

The voltage per turn of primary of transformer is _________ voltage per turn of its secondary

The voltage per turn of primary of transformer is _________ voltage per turn of its secondary:

1. Lesser than
2. Greater than
3. Equal to
4. None of these

Correct answer: 3. Equal to