1.A potential difference of 20 volts is applied across the ends of a resistance of 5 ohms. What

current will flow in the resistance?2.. A resistance of 20 ohms has a current of 2 amperes flowing in it. What potential difference isthere between its ends?3.. A current of 5 amperes flows through a wire whose ends are at a potential difference of 3volts. Calculate the resistance of the wire.4. The resistance of an electric lamp filament is 230 ohms. The lamp is switched on when theline voltage is 115 volts. What is the current in the lamp circuit?5. What is the potential difference between the ends of a conductor of 16 ohm resistance,when a current of 1.5 A flows through it?6. Calculate the work done in moving a charge of 4 coulombs from a point at 220 volts toanother point at 230 volts.7. What is the potential difference between the terminals of a battery if 250 joules of work isrequired to transfer 20 coulombs of charge from one terminal of the battery to the other?8. How much work is done in moving a charge of 2 C across two points having a potentialdifference of 12 V?9.A wire of resistance R is cut into five equal pieces. These five pieces of wire are thenconnected in parallel. If the resultant resistance of this combination be R then the ratio ofresultant to the original will be?10. A copper wire has a diameter of 0.5 mm and resistivity of 1.6 x 10 m.1. What will be the length of this wire to make its resistance 10 2ohm?2. How much does the resistance change if the diameter is doubled?11. An electric heater which is connected to a 220 V supply line has two resistance coils A andB of 24 resistances each. These coils can be used separately (one at a time), in series or inparallel. Calculate the current drawn when1. Only one coil A is used.2. Coils A and B are used in series.3. Coils A and B are used in parallel.12. If the length of a wire is doubled by taking more of wire, what happens to its resistance?13. How does the resistance of a wire change when1. Its length is tripled?2. Its diameter is tripled?3. Its material is changed to one whose resistivity is three times?14. How much energy is given to each coulomb of charge passing through a 6 V battery?15.A copper wire has a diameter of 0.5 mm and resistivity of 1.6 x 10 m.1. What will be the length of this wire to make its resistance 10 2ohm?2. How much does the resistance change if the diameter is doubled?16. The current passing through a room heater has been halved. What will happen to the heatproduced by it?17.. An electric iron of resistance 20 ohm draws a current of 5 amperes. Calculate the heatproduced in 30 seconds.18. An electric heater of resistance 8 ohm takes a current of 15 A from the mains supply line.Calculate the rate at which heat is developed in the heater.19. A resistance of 40 ohms and one of 60 ohms are arranged in series across 220 volt supply.Find the heat in joules produced by this combination in half a minute.20.State the conclusions that can be drawn from the observation that a current carrying wiredeflects a magnetic needle placed near it21 Suggest one way of discriminating a wire carrying current from a wire carrying no current?22. Name the physical quantities which are indicated by the direction of thumb and fore finger inFlemings right hand rule.23 What is the purpose of the soft iron core used in making an electromagnet? How it is differentfrom permanent magnet?24.With the help of a neat diagram describe how you can generate induced current in the circuit?25.What is an electro magnet ? Draw a circuit diagram to show how a soft iron piece can betransformed into an electro magnet?