Faraday’s law, Lenz’s law and induced emf - One Line Questions

1. If the magnetic flux through a coil is changing at a rate of 5 Wb/s, what is the magnitude of the induced emf? — 5 V
2. A metal rod of length 1 m is moving perpendicular to a magnetic field of 0.5 T with a velocity of 10 m/s. The induced emf across the ends of the rod is: — 5 V
3. A coil with 100 turns has a magnetic flux of 0.05 Wb passing through it. If this flux is reduced to 0.01 Wb in 0.1 seconds, what is the average induced emf? — 40 V
4. A coil has 50 turns and the flux through it changes from 0.2 Wb to 0.6 Wb in 0.05 seconds. The magnitude of the induced emf is: — 400 V
5. The magnetic flux through a closed loop is given by Φ(t) = 3t² + 2t + 1 Weber. The induced emf at t = 2 seconds is: — 26 V
6. A magnetic flux of 0.1 Wb passes through a coil of 200 turns. If the flux is reduced to zero in 0.01 seconds, the average induced emf is: — 20 V
7. The induced emf can be generated by: — A changing magnetic field.
8. Which of the following is a condition for electromagnetic induction? — A relative motion between a conductor and a magnetic field.
9. Faraday's first law of electromagnetic induction states that: — A changing magnetic flux induces an electromotive force (emf).
10. A square loop of side 'a' is placed in a magnetic field B. If the loop is pulled out of the field at a constant speed v, what is the rate of change of flux? — Bav
11. A conductor of length L moves with velocity v perpendicular to a magnetic field B. The induced emf is: — BLv
12. A change in magnetic flux is essential for electromagnetic induction. This change can be achieved by: — All of the above.
13. Which of the following is NOT a method to induce emf in a coil? — Increasing the resistance of the coil.
14. Lenz's law is a consequence of the law of conservation of: — Energy
15. Which quantity is conserved if Lenz's law is violated? — Energy
16. When a magnetic pole is moved towards a metallic ring, the induced current in the ring will: — Create a pole opposite to the approaching pole.
17. Consider a solenoid. If the current through the solenoid is increased, the magnetic flux through a coil placed inside the solenoid will: — Increase
18. If the number of turns in a coil is increased, what happens to the induced emf for the same rate of change of flux? — Increases
19. When a magnet is pushed into a coil connected to a galvanometer, the galvanometer needle deflects. If the magnet is pulled out, the needle will: — Deflect in the opposite direction.
20. If the area of a rectangular loop in a uniform magnetic field is halved, the magnetic flux through the loop will: — Halve
21. According to Lenz's law, the induced current opposes the change in magnetic flux. This opposition requires: — Energy input
22. The direction of induced current in a closed circuit is such that it opposes the very cause which produces it. This is the statement of: — Lenz's Law
23. If the rate of change of magnetic flux through a coil of N turns is doubled, the induced emf will be: — Doubled
24. The phenomenon of electromagnetic induction was discovered by: — Michael Faraday
25. A bar magnet is dropped through a copper ring. What will happen to the magnet as it falls? — It will fall with an acceleration less than g.
26. The induced emf is proportional to the rate of change of magnetic flux. This statement is the essence of: — Faraday's Law
27. Which of the following statements about magnetic flux is correct? — Magnetic flux is a scalar quantity.
28. The self-inductance of a coil is defined as the ratio of: — Magnetic flux linkage to the current.
29. Lenz's law helps determine which aspect of the induced current? — Direction
30. Which of the following scenarios will NOT induce an emf in a coil? — Keeping the coil stationary in a constant magnetic field.
31. If a loop of wire is moved such that it cuts magnetic field lines, an emf is induced across the ends of the loop. This is known as: — Motional EMF
32. If a conducting loop is suddenly moved into a region of uniform magnetic field, Lenz's law states that the induced current will flow in a direction that: — Opposes the motion.
33. If the magnetic flux through a loop decreases, the induced current will flow in a direction that creates a magnetic field: — In the same direction as the original field.
34. If the magnetic field through a coil is reversed, the induced emf will: — Reverse its direction.
35. When a conductor moves in a non-uniform magnetic field, an emf is induced. This is an example of: — Dynamic Induction
36. According to Lenz's Law, the induced current creates a magnetic field that: — Opposes the change in magnetic flux.
37. The unit of magnetic flux is: — Weber
38. The induced emf in a circuit is given by E = -N (dΦ/dt). What does the negative sign signify? — The induced emf is opposite in direction to the change in flux.
39. According to Faraday's second law of electromagnetic induction, the magnitude of the induced emf in a circuit is directly proportional to: — The rate of change of magnetic flux through the circuit.
40. Lenz's law is most useful for determining: — The direction of induced current.
41. Which of the following is a direct consequence of Faraday's Law of Induction? — The generation of electricity in power plants.
42. When a coil is rotated in a uniform magnetic field, the induced emf varies sinusoidally with: — Time
43. In the equation E = -N (dΦ/dt), if the magnetic flux is changing at a constant rate, the induced emf will be: — Constant
44. The unit of magnetic flux density (magnetic field strength) is: — Tesla
45. The unit of magnetic flux linkage is: — Weber
46. A current-carrying wire is moved perpendicular to a magnetic field. Will there be an induced emf in the wire? — No, only a changing magnetic flux induces emf.
47. A circular coil is placed in a uniform magnetic field. If the coil is rotated about an axis lying in its plane, the induced emf will be: — Maximum when the plane of the coil is parallel to the field.
48. A coil is connected to a battery. If the resistance of the coil is suddenly increased, the induced emf in the coil will be: — Negative
49. If the rate of change of magnetic flux is uniform, the induced emf is: — Constant
50. What is the formula for magnetic flux (Φ) through a surface area A in a uniform magnetic field B? — Φ = B ⋅ A
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