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Basic Electrical MCQs – General Science MCQs – 7

The operation of the electric generator and motor is based on the interaction between
(A) Magnetic field and electric field
(B) Magnetic field and electric current
(C) Electric field and law of induction
(D) Law of induction and dynamo-electric principle
Answer: Option B

Which of the following transformers will have smallest size with same electrical specifications?
(A) Oil Natural Air Natural (ONAN) cooled transformer
(B) Dry type transformer
(C) Oil Natural Air Forced (ONAF) cooled transformer
(D) Oil Natural Water Forced (ONWF) cooled transformer
Answer: Option D

Which parameter is increased by step up transformer?
(A) Current
(B) Resistance
(C) Voltage
(D) Frequency
Answer: Option C

Open circuit test on transformer measures
(A) Impedance and insulation resistance
(B) Voltage regulation
(C) Eddy current loss
(D) Core loss
Answer: Option D

In a step up transformer, which of the following is correct?
(A) Secondary power is more than primary
(B) Secondary current is more than primary
(C) Secondary turns are more than primary
(D) Phase shift between secondary and primary is 180°
Answer: Option C

The efficiency of a transformer is usually of the order of
(A) 33 %
(B) 50 %
(C) 75 %
(D) 98 %
Answer: Option D

The dielectric strength of transformer oil should be of the order of
(A) 415 kV
(B) 6.6 kV
(C) 11 kV
(D) 30 kV
Answer: Option D

If the secondary winding of the current transformer is opened when current is flowing in the primary current, then following will result
(A) There will be high current in the secondary winding
(B) There will be very high induced voltage in the secondary winding
(C) There will be very weak flux density in the core
(D) The transformer will burn immediately
Answer: Option B

It is possible to extend the range of an A.C ammeter by using
(A) Current transformer (CT)
(B) Shunt
(C) Capacitor
(D) Inductor coil
Answer: Option A

Which of the following voltmeters should be selected for most accurate reading?
(A) 100 V, 1 A
(B) 100 V, 100 ohms/volt
(C) 100 V, 1 mA
(D) 100 V, 100 mA
Answer: Option C