# 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