Lesson Notes By Weeks and Term v4 - JHS 1
ELECTRICITY AND ELECTRONICS
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ELECTRICITY AND ELECTRONICS
Download the Lessonotes Mobile Ghana app for faster lesson access on Android and iPhone.
Subject: Science
Class: JHS 1
Term: 2nd Term
Week: 11
Grade code: B7.4.2.2.2
Strand code: 4
Sub-strand code: 2
Content standard code: B7.4.2.2
Indicator code: B7.4.2.2.2
Theme: FORCES AND ENERGY
Subtheme: ELECTRICITY AND ELECTRONICS
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Electricity and electronics are part of daily life in Ghana—mobile phones, radios, TVs, rechargeable lamps, calculators, and even traffic lights all work because of electronic components inside them. When learners understand the function of each electronic component, they can (1) use gadgets safely, (2) troubleshoot simple faults, and (3) build simple circuits such as a battery–switch–LED circuit.
2.1 Meaning of “Electronics” (Simple idea) Electricity is the flow of electric charge (current) through a conductor. Electronics is the use of special components to control electricity (current/voltage) to perform tasks like amplifying sound, producing light, storing energy, or switching automatically.
Many gadgets contain a circuit board (PCB) with components connected by copper tracks.
2.2 Common Electronic Components and Their Functions (Core of the Indicator)
Below are components learners can see in radios, TVs, phone chargers, torches, rechargeable lamps, calculators, etc. A. Cell/Battery Function: Provides electrical energy (voltage) to push current through a circuit. Example: Two 1.5 V dry cells in series give 3.0 V to light an LED. B. Switch Function: Opens or closes a circuit to control current flow. Closed switch: circuit is complete → current flows. Open switch: circuit is broken → no current flows. C. Connecting wires / Conductors Function: Provide a path for current to flow between components. D. Resistor Function: Limits current and protects components (especially LEDs), and can reduce voltage in parts of a circuit. Where found: Radio/TV circuit boards, phone chargers, extension boards. Important note for class practical: An LED should normally have a resistor in series. However, for short demonstrations with 3 V and careful handling, it may still light briefly. Best practice is to include a resistor. E. Diode Function: Allows current to flow in one direction only (like a one-way gate). Use: Protects circuits from wrong battery connection; converts AC to DC in chargers (rectification). F. LED (Light Emitting Diode) Function: A diode that produces light when current flows in the correct direction. Polarity matters (must be connected correctly): Anode (+) connects to the positive terminal. Cathode (−) connects to the negative terminal. How to identify LED terminals (common practical method): Longer leg = Anode (+) Shorter leg = Cathode (−) Flat side on LED body usually marks the cathode (−) G. Capacitor Function: Stores electric charge temporarily and releases it when needed. Uses: Smoothing voltage in power supplies (e.g., phone chargers), timing circuits, reducing noise in radios. Real-life sign: Some capacitors are cylindrical; in old TVs/radios, faulty capacitors can cause poor sound or failure to power. H. Transistor Function: Works as an electronic switch or amplifier. Uses: Amplifies weak radio signals to drive a speaker; switching in chargers and many digital circuits. I. Fuse Function: Safety device that melts and breaks the circuit when current is too high, preventing fire and damage. Where found: Plugs, extension boards, some appliances. J. Speaker/Buzzer (Output component) Function: Converts electrical signals into sound. Where found: Radios, phones, doorbells. K. Lamp/Bulb (Output component) Function: Converts electrical energy into light (and heat). Difference from LED: Bulbs can work in either direction; LEDs require correct polarity.