Objective Questions and Answers on Transformers - Set 01 - ObjectiveBooks

Objective Questions and Answers on Transformers - Set 01

Practice Test: Question Set - 01

1. A transformer cannot raise or lower the voltage of a D.C. supply because
    (A) There is no need to change the D.C. voltage
    (B) A D.C. circuit has more losses
    (C) Faraday's laws of electromagnetic induction are not valid since the rate of change of flux is zero
    (D) None of the above

2. 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) 2 V
    (B) 20 V
    (C) 180 V
    (D) 18 V

3. In a certain transformer, the input power to the primary is 120 W. If 8.5 W are lost to the winding resistance, what is the output power to the load, neglecting any other issues?
    (A) 0 W
    (B) 14.1 W
    (C) 111.5 W
    (D) 1,020 W

4. While conducting short-circuit test on a transformer the following side is short circuited
    (A) High voltage side
    (B) Low voltage side
    (C) Primary side
    (D) Secondary side

5. In the transformer the function of a conservator is to
    (A) Provide fresh air for cooling the transformer
    (B) Supply cooling oil to transformer in time of need
    (C) Protect the transformer from damage when oil expends due to heating
    (D) None of the above

6. The purpose of providing iron core in a step-up transformer is
    (A) To provide coupling between primary and secondary
    (B) To increase the magnitude of mutual flux
    (C) To decrease the magnitude of magnetizing current
    (D) To provide all above features

7. A transformer has a 1:6 turns ratio and a secondary coil load resistance of 470 Ω. The load resistance as seen by the source is
    (A) 1.3 Ω
    (B) 7.8 Ω
    (C) 78 Ω
    (D) 13 Ω

8. The noise resulting from vibrations of laminations set by magnetic forces, is termed as
    (A) Magnetostriction
    (B) Boo
    (C) Hum
    (D) Zoom

9. Distribution transformers are generally designed for maximum efficiency around
    (A) 90% load
    (B) Zero load
    (C) 25% load
    (D) 50% load

10. Which of the following is not a routine test on transformers?
    (A) Core insulation voltage test
    (B) Impedance test
    (C) Radio interference test
    (D) Polarity test

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