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Current, Voltage and Power

1. A house is fitted with 20lamps of 60 Watt each, 10 fans consuming 0.5 Ampere each and an electric kettle of resistance 110 ohm. If energy is supplied at 220Volt and costs $3 per Kilowatt hour, Calculate the Electricity Bill for the month of April for running each appliance for six hours a day.


2.A 1kilowatt electric heater is operated at a source voltage of 220Volt. Calculate the Electric Current flowing through the coil.
a) 5.24Ampere
b) 4.55Ampere
c) 6.23Ampere
d) 2.20Ampere

3. An electric power station (100 MW) transmits power to a distant load through long and thin cables. Which of the following two modes of transmission would reasult in lesser power wastage?

a)Power Transmission at 20000V
b)Power Transmission at 200V

4. A dry cell of e.m.f. 1.5V and internal resistance of 0.10ohm is connected across a resistor in seris with a very low resistance Ammeter. When the Circuit is switched on, the ammeter reading settles to a steady value of 2Ampere.

i) What is the rate of energy dissipation inside the resistor?
ii) What is the rate of energy dissipation inside the cell?
iii) What is the rate of chemical energy consumption of the cell?
iv) What is the power output of the source?

a) 2.6W, 0.4W,3.0W,2.6W
b) 0.4W,2.6W,2.6W, 3.0W
c) 2.6W,2.6W,0.4W,3.0W
d) 3.0W,0.4W,2.6W,3.0W

5. A 230V d.c. mains source charges a series battery of 6 lead accumulators each of 2V e.m.f and internal resistance 0.25 ohm;. A load resistance of 53 ohm is connected in series.
i)What is the power supplied by the mains
ii)What is the power dissipated as heat?

a) 872W,920W
b) 920W, 872W
c) 720W,844W
d) 844W,720W

Solution Preview

Power is the rate of Work done OR Work done per unit time.
Electric Power is the rate of Work done by an Electric Current.
Electric Power = Electric Current x Electric Potential


Solution Summary

This solution is comprised of detailed explanation and step-by-step calculation of the given problems and provides students with a clear perspective of the underlying concepts.