MCQ 12 Which winding in a transformer has more number of turns?

(A) Primary winding (B) Secondary winding (C) High voltage winding (D) Low voltage winding

MCQ 1 The primary coil of a transformer is connected to a 60 V ac source. The secondary coil is connected to a 330 Ω load. The turns ratio is 3:1. What is the secondary voltage?

(A) 1 V (B) 2 V (C) 20 V (D) 40 V

MCQ 2 Which of the following properties is not necessarily desirable for the material for transformer core?

(A) High thermal conductivity (B) High permeability (C) Adequate mechanical strength (D) Low hysteresis loss

MCQ 3 If the supply frequency to the transformer is increased, the iron loss will

(A)  Increase (B) Decrease (C) Not change (D) Any of the above

MCQ 4 An ideal transformer is one which has

(A) ore of stainless steel and winding of pure copper metal (B) Interleaved primary and secondary windings (C) No losses and magnetic leakage (D) A common core for its primary and secondary winding

MCQ 5 The purpose of providing iron core in a step-up transformer is

(A) To provide all above features (B) To decrease the magnitude of magnetizing current (C) To provide coupling between primary and secondary (D)  To increase the magnitude of mutual flux

MCQ 6 A good voltage regulation of a transformer means

(A) Difference between primary and secondary voltage is least (B) Output voltage fluctuation with power factor is least (C) Difference between primary and secondary voltage is maximum (D) Output voltage fluctuation from no load to full load is least

MCQ 7 The main reason for generation of harmonics in a transformer could be

(A) Saturation of core (B) Poor insulation (C) Mechanical vibrations (D) Fluctuating load

MCQ 8 The efficiencies of transformers compared with that of electric motors of the same power are

(A) Somewhat smaller (B) Much smaller (C) Much higher (D) About the same

MCQ 9 The noise resulting from vibrations of laminations set by magnetic forces, is termed as

(A) Boo (B) Zoom (C) Magnetostriction (D) Hum

MCQ 15 A transformer cannot raise or lower the voltage of a D.C. supply because

(A) A D.C. circuit has more losses (B) Faraday's laws of electromagnetic induction are not valid since the rate of change of flux is zero (C) There is no need to change the D.C. voltage (D) None of the above

MCQ 10 Which of the following is not a routine test on transformers?

(A) Polarity test (B) Core insulation voltage test (C) Radio interference test (D) Impedance test

MCQ 11 An ideal transformer is one which has

(A) Core of stainless steel and winding of pure copper metal (B) Interleaved primary and secondary windings (C) No losses and magnetic leakage (D) A common core for its primary and secondary windings

MCQ 13 While conducting short-circuit test on a transformer the following side is short circuited

(A) Primary side (B) Low voltage side (C) Secondary side (D) High voltage side

MCQ 14 Which of the following is the main advantage of an autotransformer over a two winding transformer?

(A) Hysteresis losses are reduced (B) Eddy losses are totally eliminated (C) Saving in winding material (D) Copper losses are negligible

MCQ 16 Material used for construction of transformer core is usually

(A) Copper (B) Silicon steel (C) Aluminium (D) Wood

MCQ 17 When a 6 V battery is connected across the primary of a transformer with a turns ratio of 8, the secondary voltage is

(A) 0.75 V (B) 6 V (C) 0 V (D) 48 V

MCQ 18 Primary winding of a transformer

(A) Could either be a low voltage or high voltage winding (B) Is always a high voltage winding (C) Is always a low voltage winding (D) None of the above

MCQ 19 Which of the following loss in a transformer is zero even at full load?

(A) Hysteresis loss (B) Core loss (C) Eddy current loss (D) Friction loss

MCQ 20 In a transformer routine efficiency depends upon

(A) Supply frequency( (B) Power factor of load (C) Load current (D) Both (B) and (C)

MCQ 21 A transformer

(A) Changes dc to ac (B) Steps up or down dc voltages (C) Changes ac to dc (D) Steps up or down ac voltages

MCQ 22 A no-load test is performed on a transformer to determine

(A) Magnetizing current and loss (B) Copper loss (C) Efficiency (D) Core loss

MCQ 23 To step 110 V ac down to 20 V ac, the turns ratio must be

(A) 0.018 (B) 5.5 (C) 18 (D) 0.18

MCQ 24 Greater the secondary leakage flux

(A) Less will be the primary induced e.m.f. (B) Less will be the primary terminal voltage (C) Less will be the secondary induced e.m.f. (D) All of these

MCQ 25 The core used in high frequency transformer is usually

(A) Air core (B) Mild steel core (C) Copper core (D) Cast iron core