JEE Questions for Physics Current Electricity Ii Quiz 12 - MCQExams.com

A themocouple develops 40 µV/ kelvin. If hot and cold junctions are at 40° C and 20° C respectively, then the emf developed by a thermopile using such 150 thermocouples in series shall be
  • 150 mV
  • 80 mV
  • 144 mV
  • 120 mV
Amount of electricity required to pass through the H2O voltmeter so as to liberate 11.2 litre of hydrogen will be
  • 1 Faraday
  • 2)
    Physics-Current Electricity II-67264.png
  • 2 Faraday
  • 3 Faraday
The resistance of the filament of a lamp increases with the increase in temperature. A lamp rated 100 W, 220 V is connected across 220 V power supply. If the voltage drops by 10% then the power of lamp will be
  • 90 W
  • 81 W
  • Between 90 W and 100 W
  • Between 81 W and 90 W
In the following circuit, 18 Ω resistor develops 2 J/sec due to current flowing through it. The power developed across 10 Ω resistance is
Physics-Current Electricity II-67267.png
  • 125 W
  • 10 W

  • Physics-Current Electricity II-67268.png
  • 25 W
If resistance of the filament increases with temperature, what will be power dissipated in a 220 V¬100 W lamp when connected to 110 V power supply
  • 25 W
  • < 25 W
  • > 25 W
  • None of these
A thermal power plant produces an electric power of 600 kW at 4000 V, which is to be transported to a place 20 km away from the power plant for consumers usage. It can be transported either directly with a cable of large current carrying capacity or by using a combination of step-up and step-down transformers at the two ends.
The drawback of the direct transmission is the large energy dissipation. In the method of using transformers, the dissipation is much smaller. In this method, a step-up transformer is used to plant side so that the current is reduced to a smaller value. At the consumers end, a step-down transformer is used to supply power to the consumers at the specified lower voltage.
It is reasonable to assume that the power cable is purely resistive and the transformers are ideal with a power factor unity. All the current and voltages mentioned are rms values.
If the direct transmission method with a cable of resistance 0.4Ω km-1 is used, the power dissipation ( in % ) during transmission is
  • 40
  • 20
  • 30
  • 50
0:0:1


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