Electrical Machine - I (3140913) MCQs

MCQs of Transformers

Showing 21 to 30 out of 155 Questions
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21.
Transformer action requires a
(a) constant magnetic flux.
(b) increasing magnetic flux.
(c) alternating magnetic flux.
(d) alternating electric flux.
Answer:

Option (c)

22.
What is the coefficient of coupling for a transformer in which 10% of the total flux generated in the primary does not pass through the secondary?
(a) 0
(b) 0.90
(c) 1
(d) 1.1
Answer:

Option (b)

23.
Which parameter does not change during transformation action in a transformer?
(a) Voltage
(b) Frequency
(c) Current
(d) None of these
Answer:

Option (b)

24.
A step-up transformer increases ___________ , decreases __________ and ________________ remain constant.
(a) Voltage, Current and Power
(b) Voltage, Current and Frequency
(c) Current, Voltage and Power
(d) Current, Voltage and Frequency
Answer:

Option (b)

25.
In a step-down transformer which one statement of following is true?
(a) The number of secondary turns is less than the primary turns.
(b) secondary power is less than the primary power.
(c) secondary current is less than the primary current.
(d) the number of secondary turns is more than that of the primary.
Answer:

Option (a)

26.
The non-linear magnetization curve of a practical transformer will introduce?
(a) Heating.
(b) higher order harmonics.
(c) Magnetostriction.
(d) all of the mentioned.
Answer:

Option (d)

27.
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.
Answer:

Option (b)

28.
Transformers are rated in kVA instead of kW because
(a) load power factor is often not known.
(b) kVA is fixed whereas kW depends on load p.f.
(c) total transformer loss depends on volt-ampere.
(d) it has become customary.
Answer:

Option (c)

29.
One 200V, 100W bulb is connected in series with the primary of a 200V, 10 kVA transformer. If its secondary is open circuited, then the bulb will have
(a) full brightness.
(b) poor brightness.
(c) little less than full brightness.
(d) more than full brightness.
Answer:

Option (b)

30.
If the input of a transformer is Square Wave the output will be?
(a) Pulsed Wave.
(b) Square Wave.
(c) Triangular wave.
(d) Sine Wave.
Answer:

Option (a)

Showing 21 to 30 out of 155 Questions
1 2 3 4 5 6