1. When a particle of charge 10 ^C is brought from infinity to a point P, 2.0 mj of work is done by the external forces. What is the potential at P ?
2. Calculate the work done in taking a charge of 0.02 C from A to B if the potential at A is 20 V, and that at B is 30 V.
3. How much charge flows through a wire in 10 minutes if the current through it is 2.5 A?
4. A 2-V cell is connected to a 1-Q resistor. How many electrons come out of the negative terminal of the cell in 2 minutes?
5. The amount of charge passing through a cell in 4 seconds is 12 C. What is the current supplied by the cell?
6. A 6-V battery is connected across a 5-Ci resistor. Calculate the current passing through the resistor.
7. When a 24-V battery is connected to a resistor, the current in it is 0.4 A. What is the resistance of the resistor?
8. In an experiment, the current flowing through a resistor and the potential difference across it are measured. The values are given below. Show that these values confirm Ohm's law, and find the resistance of the resistor.
i (ampere) 1.0 1.5 2.0 2.5 3.0 V
(volt) 4.0 6.0 8.0 10.0 12
9. A current of 1.5 A flows through a wire of resistance 8 ii. Find the amount of heat produced in 10 seconds.
10. Three, resistors, each of resistance 12 Q, are connected in parallel. What is the equivalent resistance?
11. Find the current through the circuit shown in Figure 5.E1. Also find the potential difference across the 20-Q resistor.
16. A current of 2 A produces 200 J of heat in a wire in a given period of time. If the current is increased to 4 A, how much heat will be produced in the same time?
17. Calculate the resistance of a bulb rated 40 W, 230 V.
18. Calculate the current passing through a bulb rated 60 W, 240 V when it is connected to a 240-V power supply.
19. Calculate the current passing through a bulb rated 60 W, 240 V when it is connected to a supply of 220 V.
20. Calculate the energy consumed in kilowatt hours by a 60-W fan in 2 hours.
21. A heater draws 1100 W at 220 V. (a) Find the resistance of the heater, (b) Calculate the kilowatt hours consumed in a week if the heater is used daily for four hours at the rated voltage.
22. An immersion heater rated 1200 W is used to heat 10 kg of water. Calculate the time required to raise the temperature of the water from 15°C to 39°C. Specific heat capacity of water = 4200 J/ kg°C.
23. A bulb used in a car is rated 12 V, 48 W. Find the energy consumed in one minute when the bulb is connected to (a) a 12-V battery (b) a 6-V battery.
24. An electrolytic solution is taken in a voltameter. A current of 2.4 A passing through the solution for some time liberates 80 mg of a metal at the cathode. What current should be passed through the solution to liberate 120 mg of the metal if the current is to be passed for the same time.
Answers
1.200 V 2. 0.2 J 3.1500 C
4.1.5 x 1021 electrons 5. 3 A
6.1.2 A 7.60 ft 8. 4 ft
9.180 J or 43 cal 10.4 ft 11.0.2 A, 4 V
12. (a) 10 ft (b) 0.6 A (c) 0.2 A 13. 0.5 A
14. 2 A, 1 A 15.14400 J
16.800 J 17.1322.5 ft
18.0.25 A 19.0.23 A 20.0.12 kWh
21. (a) 44 Q (b) 30.8 kWh 22.14 min 23. (a) 2880 J (b) 720 J
24. 3.6 A
4.1.5 x 1021 electrons 5. 3 A
6.1.2 A 7.60 ft 8. 4 ft
9.180 J or 43 cal 10.4 ft 11.0.2 A, 4 V
12. (a) 10 ft (b) 0.6 A (c) 0.2 A 13. 0.5 A
14. 2 A, 1 A 15.14400 J
16.800 J 17.1322.5 ft
18.0.25 A 19.0.23 A 20.0.12 kWh
21. (a) 44 Q (b) 30.8 kWh 22.14 min 23. (a) 2880 J (b) 720 J
24. 3.6 A
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