Lesson Notes By Weeks and Term v4 - SHS 2
ELECTRONIC COMPONENTS AND CIRCUITS
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ELECTRONIC COMPONENTS AND CIRCUITS
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Subject: Applied Technology
Class: SHS 2
Term: 2nd Term
Week: 16
Grade code: 2.5.2.LI.3
Strand code: 5
Sub-strand code: 2
Content standard code: 2.5.2.CS.1
Indicator code: 2.5.2.LI.3
Theme: ELECTRICAL AND ELECTRONIC TECHNOLOGY
Subtheme: ELECTRONIC COMPONENTS AND CIRCUITS
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This lesson introduces learners to the inductor, a fundamental passive component in electronics. While we might not see them as often as we see light bulbs or switches, inductors are the silent workers inside many devices we use daily in Ghana—from the charger for our phone, the radio we listen to for news and music, to the ceiling fan regulators in our rooms and the large ECG transformers on our streets. Understanding how inductors work is a critical step towards mastering electronic circuits and repairs. This lesson will demystify the inductor, moving from a simple coil of wire to a powerful tool for controlling electricity.
2.1. What is an Inductor?
An inductor is a passive electronic component that stores energy in a magnetic field when electric current flows through it. In its simplest form, an inductor is just a coil of wire. Passive Component: This means it does not produce energy on its own; it can only store or dissipate it. It doesn't need an external power source to perform its basic function, unlike an active component like a transistor. The Key Principle: Resistance to Change The most important property of an inductor is that it opposes any change in the electric current flowing through it. When current starts to flow or increase, the inductor tries to stop it. When current starts to decrease or stop, the inductor tries to keep it flowing.
This property is called inductance. The unit of inductance is the Henry (H). In practical electronics, the Henry is a very large unit, so we often use smaller units: millihenry (mH): 1 mH = 0.001 H (10⁻³ H) microhenry (µH): 1 µH = 0.000001 H (10⁻⁶ H) 2.2. A Simple Analogy: The Heavy Flywheel
Imagine trying to spin a very heavy grinding wheel (like one used to sharpen a cutlass). Starting Up (Increasing Current): When you first push it, it's very hard to get it moving. It resists the change from being stationary. This is like an inductor resisting the initial flow of current. Running Steadily (Steady DC Current): Once the wheel is spinning at a constant speed, it doesn't take much effort to keep it going. This is like an inductor allowing a steady, direct current (DC) to pass through it with very little opposition (only the wire's resistance). Stopping (Decreasing Current): If you try to stop the spinning wheel suddenly, it will push back hard; it wants to keep spinning. This is like an inductor trying to keep the current flowing when the voltage source is removed or the current tries to decrease.