MULTIPLE CHOICE QUESTIONS
Q.1 A transformer transforms
(A) frequency
(B) voltage
(C) current
(D) voltage and current.
Q.2 Which of the following is not a basic element of a
transformer ?
(A) core
(B) primary winding
(C) secondary winding
(D) mutual flux.
Q.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.
Q.4 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.
Q.5 Transformer cores are laminated in order to
(A) simplify its construction
(B) minimise eddy current loss
(C) reduce cost
(D) reduce hysteresis loss.
Q.6 A transformer having 1000 primary turns is
connected to a 250-V a.c. supply. For a
secondary voltage of 400 V, the number of secondary
turns should be
(A) 1600
(B) 250
(C) 400
(D) 1250
Q.7 The primary and secondary induced e.m.fs. E1 and E2 in a two-winding
transformer are always
(A) equal in magnitude
(B) antiphase with each other
(C) in-phase with each other
(D) determined by load on transformer secondary.
Q.8 A step-up transformer increases
(A) voltage
(B) current
(C) power
(D) frequency.
Q.9 The primary and secondary windings of an ordinary
2-winding transformer always have
(A) different number of turns
(B) same size of copper wire
(C) a common magnetic circuit
(D) separate magnetic circuits.
Q.10 In a transformer, the leakage flux of each winding
is proportional to the current in that winding because
(A) Ohm’s law applies to magnetic circuits
(B) leakage paths do not saturate
(C) the two windings are electrically isolated
(D) mutual flux is confined to the core.
