12. Magnetic Effects of Electric Current

*नोट: यह सेक्शन रिवीजन के लिए है। अपना ज्ञान परखने के लिए ऊपर दिए गए क्विज़ में भाग लें।

1. What is the unit of Magnetic Field intensity?
   A) Newton  |  B) Tesla  |  C) Ampere  |  D) Ohm
2. The area around a magnet where its force can be detected is called:
   A) Electric field  |  B) Magnetic Field  |  C) Gravitational field  |  D) None of these
3. From which pole do magnetic field lines emerge?
   A) South Pole  |  B) North Pole  |  C) From the middle  |  D) Both poles
4. Who discovered the magnetic effect of electric current?
   A) Faraday  |  B) Hans Christian Oersted  |  C) Newton  |  D) Maxwell
5. Magnetic field lines intersect each other:
   A) Always  |  B) Never  |  C) At 90 degrees  |  D) Only at poles
6. The rule to find the direction of magnetic field around a current-carrying wire is:
   A) Fleming's rule  |  B) Right-hand thumb rule  |  C) Snell's law  |  D) Ohm's law
7. An insulated copper wire coil wound on a soft iron core is called:
   A) Generator  |  B) Electromagnet  |  C) Galvanometer  |  D) Resistor
8. Electric Motor converts energy:
   A) Mechanical to electrical  |  B) Electrical to mechanical energy  |  C) Thermal to electrical  |  D) None of these
9. Who discovered Electromagnetic Induction?
   A) Oersted  |  B) Michael Faraday  |  C) Volta  |  D) Ampere
10. What is the color of 'Live wire' in domestic circuits?
    A) Black  |  B) Red  |  C) Green  |  D) Blue
11. What is the color of 'Neutral wire' in domestic circuits?
    A) Red  |  B) Black  |  C) White  |  D) Yellow
12. What is the color of 'Earth wire' for safety?
    A) Red  |  B) Green  |  C) Black  |  D) Blue
13. The instrument that detects the presence of current in a circuit is:
    A) Voltmeter  |  B) Galvanometer  |  C) Ammeter  |  D) Lactometer
14. A freely suspended magnet always stays in which direction?
    A) East-West  |  B) North-South  |  C) Up-Down  |  D) Any
15. Like poles of magnets ________ each other:
    A) Attract  |  B) Repel  |  C) Don't affect  |  D) None of these
16. Magnetic field lines are:
    A) Open curves  |  B) Closed curves  |  C) Straight lines  |  D) Triangular
17. One Tesla (1 T) is equal to:
    A) 10^4 Gauss  |  B) 1 Gauss  |  C) 100 Gauss  |  D) 10 Gauss
18. Electric fuse is connected to which wire in the circuit?
    A) Neutral  |  B) Live wire  |  C) Earth wire  |  D) Any
19. What is the main source of Direct Current (DC)?
    A) Power house  |  B) Cell or Battery  |  C) Generator  |  D) None of these
20. What is the frequency of Alternating Current (AC) in India?
    A) 60 Hz  |  B) 50 Hz  |  C) 100 Hz  |  D) 0 Hz
21. In Maxwell's 'Right-hand screw rule', what does the direction of screw motion show?
    A) Magnetic field  |  B) Direction of current  |  C) Force  |  D) Potential difference
22. How is the magnetic field inside a Solenoid?
    A) Zero  |  B) Uniform at all points  |  C) Less at poles  |  D) None of these
23. What does the thumb represent in Fleming's 'Left-hand rule'?
    A) Magnetic field  |  B) Direction of force/motion on conductor  |  C) Direction of current  |  D) Potential
24. What is the function of 'Split rings' in an electric motor?
    A) Increase current  |  B) Reverse the direction of current (Commutator)  |  C) Decrease resistance  |  D) None of these
25. By which rule is the direction of induced current in electromagnetic induction found?
    A) Fleming's left-hand rule  |  B) Fleming's right-hand rule  |  C) Thumb rule  |  D) Ohm's law
26. During Overloading, the value of current in the circuit:
    A) Decreases  |  B) Increases heavily  |  C) Becomes zero  |  D) Remains constant
27. When does a Short-circuit occur?
    A) When live and neutral wires come in direct contact  |  B) When voltage increases  |  C) When switch is off  |  D) None of these
28. How do magnetic field lines look at the center of a current-carrying circular loop?
    A) Circular  |  B) Like straight lines  |  C) Spiral  |  D) None of these
29. How can the strength of an electromagnet be increased?
    A) Increasing current  |  B) Increasing number of turns  |  C) Using soft iron  |  D) All of the above
30. Where is the strength of the magnetic field highest?
    A) In the middle  |  B) Near the poles  |  C) Outside  |  D) It's zero
31. What is the direction of magnetic field lines inside a magnet?
    A) North to South  |  B) South to North  |  C) East to West  |  D) None of these
32. What is the main difference between AC and DC generators?
    A) AC has slip rings, DC has split rings  |  B) AC has no brushes  |  C) DC has oil  |  D) None of these
33. When is the force on a current-carrying conductor in a magnetic field maximum?
    A) When parallel  |  B) When perpendicular (90°) to the field  |  C) When at 45°  |  D) When stationary
34. Lenz's Law is based on which principle?
    A) Conservation of mass  |  B) Energy conservation  |  C) Conservation of charge  |  D) None of these
35. What is a Compass needle actually?
    A) Piece of iron  |  B) A small permanent magnet  |  C) A lens  |  D) A mirror
36. On which principle does an electric Generator work?
    A) Heating effect of current  |  B) Electromagnetic Induction (EMI)  |  C) Chemical effect  |  D) None of these
37. In which order are all appliances connected in domestic circuits?
    A) Series  |  B) Parallel  |  C) Mixed  |  D) None of these
38. The most suitable material for making a Permanent magnet is:
    A) Soft iron  |  B) Steel (Alnico)  |  C) Copper  |  D) Aluminium
39. What is 'Armature' in an electric motor?
    A) A switch  |  B) Combination of coil and core  |  C) A magnet  |  D) A wire
40. How is the magnetic field around a straight current-carrying conductor?
    A) Straight line  |  B) Concentric circles  |  C) Oval  |  D) None of these
41. A proton is moving towards North and magnetic field is towards East. What will be the direction of force?
    A) Downwards  |  B) Upwards  |  C) West  |  D) South
42. By how many times can the magnetic field increase by placing an iron core inside a solenoid?
    A) 2 times  |  B) By a factor of 1000s  |  C) Decreases  |  D) Remains same
43. How is a galvanometer converted into an ammeter?
    A) Adding high resistance in series  |  B) Adding low resistance (Shunt) in parallel  |  C) Removing battery  |  D) None of these
44. If the direction of AC current changes every 0.01 second, the frequency will be:
    A) 100 Hz  |  B) 50 Hz  |  C) 60 Hz  |  D) 10 Hz
45. How is the magnetic field of Earth?
    A) Like a large bar magnet  |  B) Unstable  |  C) Zero  |  D) Only at poles
46. Why is an electric fuse wire made of tin-lead alloy?
    A) Being strong  |  B) High resistivity and low melting point  |  C) Being cheap  |  D) None of these
47. Why do magnetic field lines not intersect each other?
    A) They are parallel  |  B) At point of intersection, compass cannot show two directions  |  C) They are invisible  |  D) None of these
48. What does the Forefinger represent in Fleming's right-hand rule?
    A) Direction of current  |  B) Direction of magnetic field  |  C) Direction of motion  |  D) Force
49. On making the number of turns 'n' times in a circular coil, the magnetic field:
    A) Will be 1/n times  |  B) Will increase n times  |  C) Will remain same  |  D) Will increase n^2 times
50. Why is soft iron used in electromagnets?
    A) It is cheap  |  B) It magnetizes and demagnetizes quickly  |  C) It is shiny  |  D) None of these
51. What is the function of 'Brushes' in an electric circuit?
    A) Increase current  |  B) Connect rotating armature to external circuit  |  C) Stop motor  |  D) Cleaning
52. What is the full form of MRI, which uses magnetic fields?
    A) Medical Radio Imaging  |  B) Magnetic Resonance Imaging  |  C) Main Ray Index  |  D) None of these
53. The formula for force on a current-carrying conductor in a magnetic field is:
    A) F = BIL sinθ  |  B) F = VI  |  C) F = ma  |  D) F = IR
54. If the direction of current in a conductor is reversed, what will be the effect on the direction of magnetic field?
    A) No effect  |  B) It will be reversed  |  C) Remains same  |  D) Becomes zero
55. What is the main advantage of AC over DC?
    A) Cheaper  |  B) Electric energy can be transmitted over long distances with less loss  |  C) Not dangerous  |  D) None of these
56. What is the function of 'MCB' in domestic wiring?
    A) Increase voltage  |  B) Break the circuit automatically during overloading or short-circuit  |  C) Save electricity  |  D) None of these
57. The total magnetic field at the 'Neutral Point' in a magnetic field is:
    A) Maximum  |  B) Zero  |  C) One  |  D) Infinite
58. Will current be induced by keeping a conductor stationary in a magnetic field?
    A) Yes  |  B) No (Relative motion is necessary)  |  C) A little bit  |  D) Depends on voltage
59. The power of an electric motor depends on:
    A) Value of current  |  B) Number of turns  |  C) Intensity of magnetic field  |  D) All of the above
60. What path do magnetic field lines follow outside the magnet?
    A) North Pole to South Pole  |  B) South to North Pole  |  C) Straight line  |  D) Infinity