Magnetic Effects of Electric Current MCQ Quiz

30 questions

1. A magnetic field is produced around a

   1. stationary charge
   2. current-carrying conductor
   3. plastic rod
   4. dry cell only

2. The direction of magnetic field around a straight current-carrying wire is given by the

   1. Fleming's left-hand rule
   2. right-hand thumb rule
   3. Ohm's law
   4. Snell's law

3. Magnetic field lines around a straight wire are

   1. straight lines
   2. concentric circles
   3. parabolas
   4. ellipses

4. Magnetic field lines emerge from a magnet's

   1. south pole
   2. north pole
   3. centre
   4. both poles equally

5. Two magnetic field lines

   1. intersect
   2. never intersect
   3. cross at poles
   4. overlap

6. The magnetic field inside a long solenoid is

   1. zero
   2. uniform
   3. maximum at ends
   4. circular

7. The field pattern of a current-carrying solenoid resembles that of a

   1. straight wire
   2. bar magnet
   3. circular loop only
   4. horseshoe

8. A soft iron core inside a solenoid forms an

   1. permanent magnet
   2. electromagnet
   3. insulator
   4. resistor

9. The strength of a solenoid's field increases with

   1. fewer turns
   2. more turns and more current
   3. thinner wire
   4. less current

10. The force on a current-carrying conductor in a magnetic field is given by

    1. right-hand thumb rule
    2. Fleming's left-hand rule
    3. Ohm's law
    4. Lenz's law

11. In Fleming's left-hand rule, the thumb points to the

    1. current
    2. magnetic field
    3. force/motion
    4. resistance

12. In Fleming's left-hand rule, the forefinger points to the

    1. current
    2. field
    3. force
    4. voltage

13. The force on a conductor is maximum when current is

    1. parallel to field
    2. perpendicular to field
    3. zero
    4. along the field

14. Increasing the current in a wire makes its magnetic field

    1. weaker
    2. stronger
    3. zero
    4. unchanged

15. As distance from a straight current-carrying wire increases, the field

    1. increases
    2. decreases
    3. stays same
    4. becomes zero abruptly

16. At the centre of a circular current loop, field lines appear

    1. circular
    2. straight
    3. parabolic
    4. zero

17. AC in India has a frequency of

    1. 60 Hz
    2. 50 Hz
    3. 100 Hz
    4. 25 Hz

18. AC differs from DC because AC

    1. flows one way
    2. reverses direction periodically
    3. has no voltage
    4. cannot be transmitted

19. An advantage of AC over DC is that AC can be

    1. stored easily
    2. transmitted over long distances with less loss
    3. used only in cells
    4. not transformed

20. In domestic circuits the live wire is usually insulated with

    1. green
    2. red/brown
    3. black
    4. blue

21. Assertion: The magnetic field due to a straight wire reverses when current direction reverses. Reason: Field direction depends on current direction.

    1. Both true, R explains A
    2. Both true, R not explanation
    3. A true, R false
    4. A false, R true

22. The earth wire in a domestic circuit is a

    1. safety device
    2. source of current
    3. resistor
    4. fuse

23. The device that protects circuits from excessive current is the

    1. switch
    2. fuse
    3. ammeter
    4. solenoid

24. The neutral wire in Indian domestic wiring is coloured

    1. red
    2. black/blue
    3. green
    4. brown

25. A short circuit occurs when live and neutral wires

    1. stay apart
    2. touch directly
    3. are earthed
    4. are fused

26. Overloading of a circuit happens due to

    1. too few appliances
    2. too many appliances drawing high current
    3. low current
    4. earthing

27. A compass needle near a current-carrying wire

    1. stays still
    2. deflects
    3. melts
    4. reverses poles permanently

28. The magnetic field of a bar magnet is strongest at its

    1. centre
    2. poles
    3. edges
    4. middle

29. An electromagnet loses magnetism when

    1. current stops
    2. heated only
    3. current increases
    4. turns increase

30. Domestic supply voltage in India is about

    1. 110 V
    2. 220 V
    3. 440 V
    4. 12 V

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