Lesson Notes By Weeks and Term v4 - SHS 2
ELECTROSTATICS
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ELECTROSTATICS
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Subject: Physics
Class: SHS 2
Term: 2nd Term
Week: 5
Grade code: 2.3.1.LI.4
Strand code: 3
Sub-strand code: 1
Content standard code: 2.3.1.CS.2
Indicator code: 2.3.1.LI.4
Theme: ELECTRIC FIELD, MAGNETIC FIELD AND ELECTRONICS
Subtheme: ELECTROSTATICS
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Capacitors are fundamental electronic components found in almost every device we use daily. From the ceiling fan in the classroom, to the charger for our mobile phones, and the radio we listen to for news, capacitors are quietly at work. Understanding how they behave is key to understanding modern electronics. In Ghana, where our power supply from ECG can sometimes fluctuate, devices use capacitors to protect themselves and ensure they work smoothly. This lesson will demystify these important components by exploring how they act when connected to different types of electrical sources.
2.1 What is a Capacitor?
A capacitor is an electronic component that stores electrical energy in an electric field. It is a passive component, meaning it does not produce energy. Analogy: Think of a capacitor like a *bofrot* seller's small bucket for water. The main water tank is the power source (like a battery). The seller can quickly fill the small bucket (charging the capacitor) and then quickly pour it out to wash her hands (discharging the capacitor). It holds a small amount of water (charge) for a short time. Structure: The simplest capacitor consists of two parallel conductive plates (usually metal) separated by a non-conductive material called a dielectric. The dielectric can be air, paper, ceramic, plastic, or other insulating materials.
``` Diagram of a Parallel Plate Capacitor: + + + + + + + - - - - - - | | | +-------------|-------------+ Terminal Terminal ``` Symbol: The circuit symbol for a capacitor is: `---||---` or `---|(---` for a polarized capacitor. 2.2 Capacitance (C)
Capacitance is the measure of a capacitor's ability to store an electric charge. A larger capacitance means more charge can be stored for a given voltage. Formula: Capacitance (C) is the ratio of the charge (Q) on one plate to the potential difference (V) between the plates. `C = Q / V` Units: The SI unit of capacitance is the Farad (F), named after Michael Faraday. 1 Farad is a very large unit. In practice, we use smaller units: microfarad (μF): 1 μF = 10⁻⁶ F nanofarad (nF): 1 nF = 10⁻⁹ F picofarad (pF): 1 pF = 10⁻¹² F 2.3 Behaviour of a Capacitor in a DC Circuit