Tuesday, 30 September 2014

CURRENT ELECTRICITY MULTIPLE CHOICE QUESTIONS

1. In the following figure potential difference between A and B is .


2. The lead wires should have

3. What is unit for specific resistance ?. [Rugved]

4. A metal wire of specific resistance 64 x 10-6 Ωcm and length 198 em has resistance of 7 Ω. The radius of the wire will be

5. A wire of 50 cm long and 1 mm² in cross-sectional area carries a current 4A when connected to a 2V battery. The resistivity of the wire is
6. The current from the battery in circuit diagram shown is .

7. If an ammeter is to be used in place of a voltmeter the we must connect with the ammeter a


8. An unknown resistance R1 is connected in series with a resistance of 10Ω. This combination is connected to one gap of a metre bridge while a resistance R2 is connected in the other gap. The balance point is at 50 em. Now, when the 10 Ω resistance is removed the balance position shifts to 40 em. The value of R1 is (in ohm)

9. If six identical cells each having an emf of 6 V are connected in parallel, the emf of the combination is

10. Two wires of the same dimensions but resistivities P1 and P2 are connected in series. The equivalent resistivity of the combination is
11. Identify the set in which all the three materials are good conductor of electricity

12. At what temperature will the resistance of a copper wire become three times its value at 0°C? (Temperature coefficient of resistance for copper = 4 x 10-3 per 0C)

13. Two wires of the same material are given. The first wire is twice as long as the second and has twice the diameter of the second. The resistance of the first will be


14. Potential difference between the points P and Q in the electric circuit shown is.

15. In a metre bridge experiment null point is obtained at 20 em. from one end of the wire when resistance X is balanced against another resistance Y. If X < Y, then where will be the new position of the null point from the same end, if one decides to balance a resistance of 4 X against Y
16. There are three voltmeters of the same range but of resistances 10000 Ω, 8000 Ω and 4000 Ω respectively. The best voltmeter among these is the one whose resistance is

17. If in the circuit shown, the internal resistance of the battery is 1.5 Ω and VP and VQ are the potentials at P & Q respectively what is the potential difference between P and Q .

18. In a typical Wheatstone network the resistances in cyclic order are A = 10 Ω, B = 10 Ω, C = 4 nand D = 4 Ω. For the bridge to be balanced.


19. The resistance of 20 em long wire is 5 ohm. The wir~ is stretched to a uniform wire of 40 em length. The resistance now will be (in ohms)


20. If a wire of resistance R is melted and recasted to half of its length, then the new resistance of the wire will be. [KCET (Med.) 200]

21. A cell of internal resistance 3 ohm and emf 1 volt is connected to a uniform wire of length 500 em and resistance 3 ohm. The potential gradient in the wire is


22. Four resistances are connected in a circuit in the given figure. The electric current flowing through 4 ohm a 6 ohm resistance is respectively .

23. The resistance of a conductor is 5 ohm at 50°C and 6 ohm at 100°C. Its resistance at 0°C is

24. The potential difference between points A and B of adjoining figure is .

25. Two wires A and B of same material and same mass have radius 2 r and r. If resistance of wire A is 34 Ω, then resistance of B will be

26. Which of the following does not obey Ohm's law

27. The equivalent resistance of the following diagram between A and B is.

28. The resistors of resistances 2 Ω, 4 Ω and 8 Ω are connected in parallel, then the equivalent resistance of the combination will be


29. By increasing the temperature, the specific resistance of a conductor and semiconductor

30. The resistivity of a wire depends on its

31. Read the following statements carefully Y: The resistivity of a semiconductor decreases with increase of temperature Z : In a conducting solid, rate of collisions between free electrons and ions increases with increases of temperature Select the correct statements (s) from the following


32. A uniform wire of resistance R is uniformly compressed along its length, until its radius becomes n times the original radius. New resistance of the wire becomes

33. The internal resistance of a cell is the resistance of

34. A wire of resistance 10 Ω is bent to form a circle,Pand Q are points on the circumference of the circle dividing it into a quadrant and are connected to a battery of 3 V and internal resistance 1 Ω as shown in the figure. The currents in the two parts of the circle are .


35. Two resistance wires on joining in parallel, the resultant resistance is 6/5 Ω. One of the wire breaks. The effective resistance is 2 Ω. The resistance of the brokes wire was


36. Six identical cells of emf E and internal resistance r are connected in parallel, then the net emf and internal resistance of the combination will be

37. The resistance of a wire is R. If the length of the wire is doubled by stretching, then the new resistance will be

38. Resistances of 6 ohm each are connected in the manner shown in adjoining figure. With the current ampere as shown in figure, the potential difference VP - VQ is .


39. Two resistance r1 and r2 (r1 < r2 ) are connected in parallel. Their equivalent resistance R is

40. An ammeter reads upto 1 ampere. Its internal resistance is 0.81 ohm. To increase the range to 10 A the value of the required shunt is

41. In the given figure, when galvanometer shows no deflection, the current (in ampere) flowing through 5Ω resistance will be.

42. When cells are arranged in parallel


43. A uniform wire of resistance 9 n is cut into 3 equal parts. They are connected in the form of equilateral triangle ABC. A cell of emf 2V anj negligible internal resistance is connected across B and C. Potential difference across AB is


44. The internal resistance of a cell of emf 12 V is 5 x 10 -2 Ω . It is connected across an unknown resistance. Voltage across the cell, when a current of 60 A is drawn from it, is


45. Two cells each of emf E and internal resistance r are connected parallel across a resistor R. The power dissipated in the resistor is maximum if

46. If the current through 3 n resistor is 0.8 A then the potential drop through 4 Ω resistor is.

47. Three resistors are connected to form the sides of a triangle ABC, the resistance of the sides AB, BC and CA are 40 ohms; 60 ohms and 100 ohms respectively. The effective resistance between the points A and B in ohms will be. [JIPMER 2002]


48. The resistance of a coil is 4.2 Ω at 100°C and the temperature coefficient of resistance of its material is 0.004 °C. Its resistance at Q °C is

49. The resistance of an incandescent lamp is

50. The number of dry cells, each of emf 1.5 volt and internal resistance 0.5 ohm that must be joined in series with a resistance of 20 ohm so as to send a current of 0.6 ampere through the circuit is