Basic Electrical Engineering

1. All sine waves

  1. Have similar general appearance
  2. Have instantaneous rise and fall times
  3. Are in the same phase as cosine waves
  4. Rise instantly, but decay slowly

Correct answer: (A)
Have similar general appearance

2. The location of lighting arrestor is?

  1. Near the transformer
  2. Near the circuit breaker
  3. Away from the transformer
  4. None

Correct answer: (D)

3. The principle of operation of a 3 phase induction motor is most similar to that of a

  1. synchronous motor
  2. repulsion start induction motor
  3. transformer with a shorted secondary
  4. capacitor start, induction run motor

Correct answer: (C)
transformer with a shorted secondary

4. Which of the following is not a general characteristic of ac wave?

  1. The wave shape is identical for each cycle
  2. The polarity reverses periodically
  3. The electrons always flow in the same direction
  4. There is a definite frequency

Correct answer: (C)
The electrons always flow in the same direction

5. A battery has a short-circuit current of 30A and an open circuit voltage of 24V. If the battery is connected to an electric bulb of resistance 2 ?, the power dissipated by the bulb is

  1. 80W
  2. 1800W
  3. 112.5W
  4. 228W

Correct answer: (C)

6. A battery is source of

  1. DC voltage
  2. 1 phase AC voltage
  3. 3 phase ac voltage
  4. ac or dc voltage

Correct answer: (A)
DC voltage

7. A BJT has

  1. three PN junctions
  2. three semiconductor layers
  3. two N type layers around a P type layer
  4. a low avalanche voltage

Correct answer: (B)
three semiconductor layers

8. A capacitor is charged by a constant current of 2mA and results in a voltage increase of 12V in a 10 sec interval. The value of capacitance is

  1. 0.75mF
  2. 1.33mF
  3. 0.6mF
  4. 1.67mF

Correct answer: (D)

9. A common-collector transistor circuit is often used

  1. to provide high gain and sensitivity over a wide range of frequencies
  2. to match a high impedance to a low impedance
  3. as a high-fidelity audio power amplifier
  4. as an oscillator at microwaves frequencies
  5. as the rectifier in a dc power supply.

Correct answer: (B)
to match a high impedance to a low impedance

10. A complex wave form made up frequency components 1 Hz, 3 Hz, 5 Hz, 7 Hz and 9 Hz. Its fundamental frequency is

  1. 9 Hz
  2. 12.5 Hz
  3. 1 Hz
  4. Indeterminate

Correct answer: (C)
1 Hz

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