Objective Questions from Transformers
[1] A transformer transforms
A. Frequency
B. Voltage
C. Current
D. Voltage and current
[2] Which is not the basic element of the transformer?
A. Core
B. Primary winding
C. Secondary winding
D. Mutual flux
[3] In an ideal transformer
A. Windings have no resistance
B. Core has no losses
C. Core has infinite permeability
D. All of the above
[4] The frequency of the secondary voltage of a transformer will be.....
A. Less than frequency of the primary voltage
B. Equal to the primary voltage
C. Greater than the frequency of the primary voltage
D. Much greater than the frequency of the primary voltage
[5] The efficiency of a transformer is maximum when
A. It runs at half full load
B. It runs at full load
C. Its Cu loss equal iron loss
D. It runs over load
[6] A step-up transformer increases
A. Voltage
B. Current
C. Power
D. Frequency
[7] Which type of loss is not common to transformer and rotating machines?
A. Eddy current loss
B. Copper loss
C. Hysteresis loss
D. Windage loss
[8] The transformer core is laminated to
A. Reduce the copper losses
B. Reduce the core losses
C. Reduce the eddy current losses
D. None of the above
[9] Transformer cores are built up from laminations rather than from solid metal so that
A. Oil penetrates the core more easily
B. Eddy current loss is reduced
C. Less lamination is required for the windings
D. Turn ratio is higher than voltage ratio
[10] The main purpose of using core in a transformer is to
A. Decrease iron losses
B. Prevent eddy current loss
C. Eliminate magnetic hysteresis
D. Decrease reluctance of the common magnetic circuit
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