Electronics and Communication Engineering

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The frame of electric motor is connected to three plates having earthing resistance of 10 Ω, 20 Ω and 30 Ω respectively. The materials of the three plates are copper, aluminium and iron respectively. The percentage of energy dissipated by 10 Ω earthing plate

The frame of electric motor is connected to three plates having earthing resistance of 10 Ω, 20 Ω and 30 Ω respectively. The materials of the three plates are copper, aluminium and iron respectively. The percentage of energy dissipated by 10 Ω earthing plate
  • A. is more than 50% of total energy
  • B. is less than 50% of total energy
  • C. depends on the materials of the three plates
  • D. may be more or less than 50% of total energy
  • Correct Answer: Option A

A sawtooth current wave is passed through a resistance

A sawtooth current wave is passed through a resistance
  • A. the waveshapes of voltages across resistance and power will also the sawtooth
  • B. the waveshape of voltage across resistance will be sawtooth
  • C. the waveshape of power will be sawtooth
  • D. neither the voltage waveshape nor power wave-shape will be sawtooth
  • Correct Answer: Option B

The voltage of single phase supply to residential consumers in India is

The voltage of single phase supply to residential consumers in India is
  • A. 400 V
  • B. 230 V
  • C. 2.2 kV
  • D. 11 kV
  • Correct Answer: Option B

The distributors for residential areas are

The distributors for residential areas are
  • A. single phase
  • B. three phase three wire
  • C. three phase 4 wire
  • D. (a) or (b)
  • Correct Answer: Option C

The minimum permissible size of aluminium cable for lighting circuit is

The minimum permissible size of aluminium cable for lighting circuit is
  • A. 1.2 sq. mm
  • B. 1.5 sq. mm
  • C. 2.2 sq. mm
  • D. 3.5 sq. mm
  • Correct Answer: Option B

The purpose of earthing electric appliances is

The purpose of earthing electric appliances is
  • A. to provide safety against shock
  • B. to ensure that appliance works satisfactorily
  • C. to ensure that appliance gets full voltage
  • D. all of the above
  • Correct Answer: Option A

The total lumens emitted by a source of 1 candle are

The total lumens emitted by a source of 1 candle are
  • A. 0.4
  • B. 4
  • C. 2
  • D. 8
  • Correct Answer: Option B