Objectives MCQs on Transformer 

1). In a certain loaded transformer, the secondary voltage is one-fourth the primary voltage the secondary current is

a)    One-fourth the primary current

b)    four times the primary current

c)    equal to the primary current

d)    one-fourth the primary current or equal to the primary current

Answer: b)

2). Which of the following are variable losses ?

a)    Eddy current loss

b)    hysteresis loss

c)    shunt field copper loss   

d)    armature copper loss  

Answer: d) Armature copper loss is directly proportional to square of armature current. Therefore as the load varies these will also varies

3). The noise resulting from vibrations of lamination set by magnetic forces, is termed as

a)    Magnetostriction    

b)    boo

c)    hum.

d)    zoom

Answer: c)

4). The primary winding of a power transformer should always be

a)    open   

b)    shorted

c)    Switched

d)    fused

Answer: d)

5). Eddy current loss will depends on

a)    Frequency  

b)    Flux density

c)    Thickness

d)    All of the above

Answer: d) 

,So Eddy current loss will depends on frequency ,flux density and the are of eddy current loop

6).Hysteresis loss will depends on

a)    f

b)    f²

c)    f³

d)    f^1.6

Answer: a) 

so hysteresis loss will depends on frequency

7). Total core losse is also called as ---------?

a)    Eddy current loss  

b)    Hysteresis loss

c)    Magnetic loss

d)    copper loss

Answer: c) As iron loss is proportional to flux density or flux, these are also called as magnetic loss. the total core loss or magnetic loss consist of eddy current loss and hysteresis loss.

8). Maximum efficiency will occur, when the copper loss is_________to iron loss?

a)    Greater than

b)    Less than

c)    Equal to

d)    Any of the above

Answer: c) The condition for maximum efficiency is, copper loss = iron loss or variable losses is equal to fixed losses.

9). The basic function of a transformer is to change

a)    The power level

b)    The power factor

c)    The level of the voltage    

d)    The frequency

Answer: c) A transformer can be used for ether step up or step down the voltage without changing frequency.

10). The core flux in transformer depends mainly on

a)    Supply voltage

b)    Supply voltage and Frequency

c)    Supply voltage , Frequency and Load

d)    Supply voltage and Load

Answer: b)