**21. Power transformed from primary to secondary depends upon**

- number of primary turns
- number of secondary turns
- current transformation ratio
- magnetic coupling between primary and secondary windings

**22. A transformer is supplying pure resistive load. The power factor on primary side will be**

- about 0.95(lead)
- about 0.95(lag)
- zero
- unity

**23. The phasor diagram of a transformer on load can be drawn only if we know**

- equivalent circuit parameters of the transformer
- load current
- load power factor
- all of the above

**24. In the transformer circuit mode, the core loss is represented as a**

- series resistance
- series inductance
- shunt resistance
- shunt inductance

**25. In a transformer, zero voltage regulation at full load is**

- not possible
- possible at leading power factor load
- possible at lagging power factor load
- possible at unity power factor load

**26. Positive voltage regulation is an indication of _______ load.**

- inductive
- capacitive
- either inductive or capacitive
- pure resistive

**27. Which of the following is the constant power loss in transformer?**

- Copper loss
- Hysteresis loss
- Eddy current loss
- Both Hysteresis and Eddy current loss

**28. In a power transformer, iron losses remain practically constant from no load to full load. This is because**

- core flux remains constant
- leakage flux remains constant
- both core flux and leakage remains constant
- neither core flux and leakage remains constant

**29. Hysteresis loss depends on which of the following factors?**

- load current
- frequency and flux density
- thickness of laminations
- time

**30. The main purpose of performing open circuit on a transformer is to measure its**

- copper loss
- core loss
- total loss
- insulation resistance