Self and mutual inductance and eddy currents - One Line Questions

1. The magnetic flux linkage in a coil is given by NΦ. If the current changes by ΔI and the flux changes by ΔΦ, the induced emf is given by: — -Δ(NΦ)/Δt
2. Two coils have a mutual inductance of 5 mH. If the current in the first coil changes from 1 A to 2 A in 0.05 s, the magnitude of the induced emf in the second coil is: — 0.1 V
3. If the current in a coil changes from 0 to 2 A in 0.1 s and the induced emf is 10 V, the self-inductance of the coil is: — 0.5 H
4. The coefficient of mutual induction between two coils is 10 mH. If a current of 2 A flows through one coil, the magnetic flux linked with the other coil is: — 10 mWb
5. If the rate of change of current in a coil of inductance 0.5 H is 20 A/s, the magnitude of the induced emf is: — 10 V
6. A changing magnetic flux through a conductor induces: — An emf.
7. The ratio of self-inductance to mutual inductance for two tightly coupled coils is: — Always equal to 1.
8. In a variable inductor, the inductance is changed by: — Changing the geometry or position of the core.
9. Lenz's Law is a consequence of the conservation of: — Energy
10. The property of a coil that opposes the change in current flowing through it is called: — Inductance
11. Eddy currents are induced in a metallic core when it is placed in a: — Changing magnetic field.
12. Eddy currents are: — Currents induced in a conductor when it is exposed to a changing magnetic field.
13. Eddy currents are also known as: — Circulating currents.
14. If the magnetic flux through a coil is doubled, the induced emf will: — Double.
15. Eddy currents are used in: — Induction furnaces.
16. Which of the following applications utilizes the principle of eddy currents? — Induction heating.
17. The unit of inductance is: — Henry
18. If the number of turns in a coil is doubled, its self-inductance will: — Become four times.
19. Mutual inductance is a measure of: — How much emf is induced in one coil due to a changing current in another coil.
20. If the current in a coil of self-inductance L is I, the magnetic energy stored is proportional to: — I^2
21. A solid iron core is used in a transformer to: — Increase magnetic flux linkage.
22. Eddy current losses in transformers are reduced by: — Using thin, insulated laminations for the core.
23. Which of the following statements about inductance is correct? — Inductance is the ratio of magnetic flux to current.
24. Eddy currents are undesirable in: — Transformers.
25. For two inductively coupled coils, the coupling coefficient 'k' is defined as: — k = M / sqrt(L1 * L2)
26. If two coils with self-inductances L1 and L2 are connected in series such that their fluxes add, the total inductance is: — L1 + L2 + 2M
27. The energy stored in an inductor is given by: — 1/2 * LI^2
28. Mutual inductance (M) between two coils is defined by the relation: — M = N_1 * Phi_12 / I_1 = N_2 * Phi_21 / I_2
29. The coefficient of self-inductance of a coil is numerically equal to the: — Magnetic flux linkage when a unit current flows through the coil.
30. The phenomenon of electromagnetic induction is described by: — Faraday's Law
31. The self-inductance of a circular coil of radius 'r' and 'N' turns carrying current 'I' is approximately proportional to: — r^2
32. Which physical quantity is represented by the symbol 'L' in electrical circuits? — Inductance
33. The self-inductance of a coil depends on its: — Geometry and magnetic properties of the core.
34. The direction of the induced current in Lenz's law is such that it: — Opposes the change in magnetic flux.
35. What is the SI unit of magnetic flux? — Weber
36. The unit of magnetic flux is: — Weber
37. What is self-inductance? — The ability of a coil to oppose changes in its own magnetic flux.
38. The coefficient of coupling 'k' between two coils is zero when: — There is no magnetic flux linkage between the coils.
39. Eddy currents are induced when a conductor moves relative to a magnetic field or when: — The magnetic field through the conductor changes.
40. Which of the following factors does NOT affect the mutual inductance between two coils? — The current flowing in one of the coils.
41. The self-inductance of a coil is independent of: — The current flowing through it.
42. The self-inductance of a long solenoid is directly proportional to: — The square of the number of turns per unit length.
43. Mutual inductance between two coils depends on: — All of the above.
44. Which of the following is a method to reduce eddy currents? — Using a laminated core.
45. In a transformer, eddy currents are minimized by: — Laminating the core with insulating layers.
46. Which of the following is a unit of inductance? — Volt-second/Ampere
47. The unit of magnetic flux density is: — Tesla
48. A coil of inductance 2 H is connected to a DC source. If the current is switched off instantaneously, the induced emf will be: — Finite and depends on the rate of current change.
49. The self-inductance of a straight wire is: — Zero.
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