Chapter 5 : MAGNETIC EFFECTS OF ELECTRIC CURRENT

Choose Appropriate Alternative

1. The direction of magnetic field lines in the region outside the bar magnet is...
   

   [A] from the N pole towards the S pole of the magnet. 
   [B] from the S pole towards the N pole of the magnet.
   [C] in the direction coming out from both the poles of the magnet.
   [D] in the direction entering both the poles of the magnet.

2. Which of the following statements is false?
   

   [A] The direction of magnetic field lines is from N to S.
   [B] In the region where magnetic field lines are at a close distance from one another, 
   there will be a strong magnetic field. 
   [C] The magnetic field lines form closed loops. 
   [D] The magnetic field lines can cross one another.

3. By which instrument can the presence of magnetic field be determined?
   

   [A] Voltmeter [B] Ammeter [C] Galvanometer [D] Magnetic needle

4. Who was the first to observe the magnetic effect of electric current?
   

   [A] Faraday [B] Oersted [C] Volta [D] Ampere

5. With the help of which law can the direction of a magnetic field decided?
   

   [A] Faraday's law          [B] Fleming's right hand rule 
   [C] Right hand thumb rule  [D] Fleming's left hand rule

6. According to the Right hand thumb rule, direction of what is indicated by the thumb?
   

   [A] Electric current [B] Magnetic field [C] Magnetic force [D] Motion of conductor

7. The magnetic field produced in a straight conducting wire on passing current through it is...
   

   [A] in the direction of current [B] in the direction opposite to the current 
   [C] circular around the wire    [D] in the direction parallel to the wire

8. What is the type of field line of a magnetic field passing through the centre of current carrying circular ring?
   

   [A] Circular [B] Straight line [C] Ellipse [D] Magnetic field is zero at centre.

9. Which of the following has magnetic field like that of a bar magnet?
   

   [A] Current carrying wire     [B] Current carrying ring 
   [C] Current carrying solenoid [D] Current carrying rectangular loop

10. Who gave the principle of electromagnetic induction?
    

    [A] Faraday [B] Oersted [C] Volta [D] Ampere

11. Which is the direction of magnetic force acting on a current carrying wire placed in a magnetic field?
    

    [A] along magnetic field            [B] along the electric current 
    [C] perpendicular to magnetic field [D] opposite to magnetic field

12. How is a current carrying wire placed in a magnetic field so that magnetic field does not act on it?
    

    [A] Parallel to the magnetic field             [B] Perpendicular to the magnetic field 
    [C] Making angle of 40° with magnetic field [D] Can be arranged any way.

13. In which of the following cases, the induced current in the loop will not be obtained?
    

    [A] The loop is moved in the direction of the magnet. 
    [B] The magnet is moved in the direction of the loop.
    [C] The loop and the magnet are moved in opposite direction with same speed.
    [D] The loop and the magnet are moved in one direction with same speed.

14. Which instrument is used for converting electrical energy into mechanical energy?
    

    [A] Electric generator [B] Electric motor [C] Electric iron [D] Electric oven

15. On which principle does the electric generator work?
    

    [A] Electrical energy is converted to mechanical energy.
    [B] Electrical energy is converted to thermal energy.
    [C] Mechanical energy is converted to electrical energy.
    [D] Electrical energy is converted to light energy.

16. The magnitude of AC voltage used in India is _____ and the frequency is _____.
    

    [A] 110V, 60Hz [B] 110V, 50Hz [C] 220V, 50Hz [D] 220V, 60Hz

17. Which coloured insulation cover is used for earthing wire?
    

    [A] Red [B] Black [C] Green [D] Can be of any colour

18. Which type of current is obtained from a battery?
    

    [A] AC [B] DC [C] Both AC and DC [D] Depends on type of battery

19. Which of the following instruments is used to know the presence of electric current?
    

    [A] Fuse [B] Galvanometer [C] Voltmeter [D] Magnetic needle

20. A fuse wire is...
    

    [A] a conductor [B] an insulator [C] a semi-conductor [D] made of any material

21. ______ is the rule used to know the direction of the induced current in the circuit.
    

    [A] Fleming's left hand rule [B] Fleming's right hand rule 
    [C] Right hand thumb rule    [D] Ampere's rule

22. How many times does an Alternating current (AC) with frequency 50Hz change its direction?
    

    [A] 25 [B] 50 [C] 100 [D] 200

23. At the centre of which of the following four circular rings the magnetic field is the strongest for equal magnitude of current?
    
    
    
    

    [A] Figure A [B] Figure B [C] Figure C [D] Figure D

24. The magnetism of magnets is maximum...
    

    [A] at poles [B] at the centre [C] at the axis [D] everywhere in the magnet

25. Within a bar magnet, the magnetic field lines are...
    

    [A] from N to S [B] from S to N [C] absent [D] in both directions

26. The strength of magnetic field produced in a current carrying straight conductor is...
    

    [A] directly proportional to the distance from the wire 
    [B] directly proportional to the magnitude of the current in wire
    [C] inversely proportional to the magnitude of the current in wire
    [D] independent of the magnitude of the current in wire

27. The magnetic field inside a solenoid is...
    

    [A] strong at N pole and weak at S pole
    [B] strong at S pole and weak at N pole
    [C] uniform throughout 
    [D] zero

28. What is not true?
    

    [A] A solenoid is an electromagnet. [B] A solenoid is a temporary magnet.
    [C] A solenoid is a permanent magnet. [D] A solenoid is like a bar magnet.

29. A fuse wire is generally made of...
    

    [A] copper [B] aluminium [C] alloy of lead and tin [D] alloy of copper and lead

30. In our domestic electric supply, we use following three colours of insulation cover on wires:
    

    [A] Red, blue, green     [B] Red, yellow, blue
    [C] Black, green, yellow [D] Red, black, green

31. The current passing through two separate lines (circuits) of our houses is _____ A and _____ A.
    

    [A] 5, 10 [B] 5, 15 [C] 10, 15 [D] 2, 5

32. Which of the following is not a permanent magnet?
    

    [A] Magnetic needle [B] Bar magnet [C] Electromagnet [D] Horse-shoe magnet

33. The force experienced by a current carrying wire placed in a magnetic field will be maximum when it is...
    

    [A] at an angle of 45° to the magnetic field 
    [B] at right angle to the magnetic field 
    [C] parallel to the magnetic field 
    [D] anti-parallel to the magnetic field

34. A magnetic field will not exert force on...
    

    [A] a bar magnet     [B] a stationary electric charge
    [C] an electromagnet [D] an electric charge moving perpendicularly to it

35. On which of the following does the electromotive force not depend?
    

    [A] The relative motion of the coil and magnet [B] Number of turns 
    [C] Rate of change of flux linked with the coil[D] Material of the coil

36. During the situation of short-circuit, the current in the circuit...
    

    [A] reduces to zero [B] increases greatly [C] does not change [D] oscillates

37. If many appliances are connected in a circuit, _____ may occur.
    

    [A] short-circuit [B] long-circuit [C] over loading [D] explosion

38. At the centre of which of the following four circular rings the magnetic field is the strongest for equal magnitude of current?
    
    
    
    

    [A] Loop 1 [B] Loop 2 [C] Loop 3 [D] Loop 4

39. Match the following in Part A with appropriate alternative in Part B.
    
    
    
    

    [A] 1-b, 2-c, 3-d, 4-a [B] 1-c, 2-d, 3-b, 4-a
    [C] 1-a, 2-d, 3-b, 4-c [D] 1-a, 2-c, 3-d, 4-b

40. What is the potential difference of the current flowing in the insulated wires in America?
    

    [A] 220 V [B] 100 V [C] 110 V [D] 60 V

41. _____ current line is connected to the air-conditioning machine.
    

    [A] 20 A [B] 15 A [C] 10 A [D] 5 A

42. If the current flowing through each turn of a solenoid is in the same direction, the magnetic field produced by n turns will be ____ with the magnetic field due to each turn.
    

    [A] added [B] subtracted [C] multiplied [D] divided

43. The magnitude of the induced current due to the relative motion of coil and a magnet does not depend on...
    

    [A] speed of the relative motion [B] number of turns of coil
    [C] resistivity of wire of coil  [D] pole strength of the magnet

44. Which of the following statements is not suitable with reference to Direct Current(DC)?
    

    [A] Electric current flows always from positive pole to negative pole.
    [B] The value of electric current is always constant with time.
    [C] Its production is cheap
    [D] More energy is wasted in its conduction

45. 
    

    [A][B][C][D]

46. 
    

ANSWERS

(1) A (2) D (3) D (4) B (5) C (6) D (7) C (8) B (9) C (10) A (11) C (12) A (13) D (14) B (15) C (16) C (17) C (18) B (19) B (20) A (21) B (22) C (23) A (24) A (25) B (26) B (27) C (28) C (29) C (30) D (31) B (32) C (33) B (34) B (35) D (36) B (37) C (38) D (39) D (40) C (41) B (42) C (43) C (44) C (45)