Inductance | Jamb(UTME)

Explanation of Inductance

1. Inductance is the property of a conductor or coil that opposes changes in current.
2. It occurs because a changing current produces a changing magnetic field, inducing a voltage (emf) in the conductor itself.
3. The induced emf opposes the change in current, following Lenz's Law.
4. Inductance depends on the number of turns in the coil, the coil’s area, and the type of core material.
5. A coil with more turns has higher inductance.
6. A larger coil area allows more magnetic flux, increasing inductance.
7. Using a magnetic core like iron enhances inductance because it increases the magnetic flux.
8. The induced emf $(emf)$ is directly proportional to the rate of change of current:
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   $emf = -L \frac{dI}{dt}$ where:
   • $L$: Inductance,
   • $\frac{dI}{dt}$: Rate of change of current.
9. Inductance is often compared to inertia in mechanics because it resists changes in current.
10. Inductors store energy in the form of a magnetic field when current flows through them.
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Unit of Inductance

11. The unit of inductance is the Henry (H).
12. One Henry is the inductance when a current changing at the rate of 1 ampere per second induces an emf of 1 volt.
13. Smaller units of inductance include millihenry (mH) and microhenry (µH).
14. The Henry is a large unit, so inductors in practical circuits often have values in mH or µH.
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Energy Stored in an Inductor

15. An inductor stores energy when current flows through it, creating a magnetic field.
16. The energy stored depends on the inductance and the current:
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    $E = \frac{1}{2} L I^2$ where:

• $E$: Energy stored (in joules),
• $L$: Inductance (in Henrys),
• $I$: Current (in amperes).

17. When the current increases, the inductor stores more energy.
18. The energy is stored in the magnetic field surrounding the inductor.
19. If the current is interrupted, the inductor releases the stored energy.
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Applications/Uses of Inductors

In Electrical Circuits

20. Inductors are used in filters to block or pass specific frequencies.
21. In low-pass filters, inductors block high-frequency signals.
22. In high-pass filters, inductors allow high-frequency signals to pass.
23. Inductors are used in LC circuits (inductor-capacitor circuits) to create oscillators.
24. In resonance circuits, inductors help tune radios and televisions to specific frequencies.
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In Power Systems

25. Inductors are used in transformers to transfer energy between circuits.
26. In chokes, inductors block high-frequency noise in power supplies.
27. Inductors help stabilize current in DC power supplies by smoothing out fluctuations.
28. Inductors limit the surge of current when turning on devices, protecting circuits.
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In Communication Systems

29. Inductors are used in antennas for signal transmission and reception.
30. In radio frequency circuits, inductors help select desired frequencies.
31. Inductors are part of the tuning system in AM/FM radios.
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In Energy Storage and Conversion

32. Inductors store energy temporarily in inductive energy storage systems.
33. They are used in inductive charging systems, like wireless phone chargers.
34. In solar inverters, inductors smooth out the DC-AC conversion process.
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In Electrical Machines

35. Inductors are integral to the working of electric motors and generators.
36. They are used in induction coils to generate high voltages.
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Other Applications

37. Inductors are used in metal detectors to detect metallic objects.
38. In traffic light sensors, inductors detect vehicles through changes in inductance.
39. Inductors are part of magnetic levitation (maglev) systems for trains.
40. They are used in inductive sensors for position or motion detection.
41. Inductors play a role in X-ray machines for controlling power.
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Properties and Limitations

42. Inductors resist sudden changes in current, making them essential in surge protection.
43. The inductance value depends on the geometry and core material.
44. Inductors are often bulky compared to capacitors with equivalent roles.
45. Energy losses occur in inductors due to resistance (ohmic losses) and core heating.
46. Eddy currents in the core material can reduce efficiency, which is mitigated by laminating the core.
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Inductors in Everyday Devices

47. Inductors are found in speakers, helping produce clear audio by smoothing signals.
48. In fluorescent lamps, inductors help regulate current flow.
49. In computer power supplies, inductors stabilize voltages.
50. Inductors are used in refrigerators and air conditioners for compressor motor operation.
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