Lesson Notes By Weeks and Term v4 - SHS 3
ELECTRONIC COMPONENTS AND CIRCUITS
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ELECTRONIC COMPONENTS AND CIRCUITS
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Subject: Applied Technology
Class: SHS 3
Term: 2nd Term
Week: 19
Grade code: 2.5.2.LI.10
Strand code: 4
Sub-strand code: 2
Content standard code: 2.5.2.CS.1
Indicator code: 2.5.2.LI.10
Theme: ELECTRICAL AND ELECTRONIC TECHNOLOGY
Subtheme: ELECTRONIC COMPONENTS AND CIRCUITS
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Imagine you are in Accra and you want to share exciting news with your friend in Tamale. If you just shout, your voice (the sound signal) will not travel that far. However, if you speak into a radio presenter's microphone at Peace FM, your voice can be heard clearly in Tamale and even beyond. How is this possible? The "magic" that makes this happen is called modulation. It is the process of placing our low-energy information (like our voice) onto a high-energy wave that can travel very long distances. Understanding modulation is key to understanding how radio, television, and even our mobile phones work.
This section breaks down the core ideas you need to understand. We will build them up step-by-step. Focal Area 1: The Carrier Wave
A carrier wave is a high-frequency, high-energy electromagnetic wave that is used to "carry" a lower-frequency information signal (like voice or music) from a transmitter to a receiver over a long distance. Think of it like this: Imagine you want to send a letter (your message) from Accra to Kumasi. You cannot just throw the letter and expect it to reach. You need to put the letter on a delivery truck or a bus (the carrier). The bus is designed to travel long distances efficiently. Your Message (Letter): Low frequency, low energy (e.g., your voice signal). The Carrier (Bus): High frequency, high energy. Characteristics of a Carrier Wave: High Frequency: It oscillates very rapidly. This allows it to travel long distances with less power loss and requires a much smaller, more practical antenna. Constant Amplitude, Frequency, and Phase: Before modulation, a pure carrier wave is stable and predictable. It's a blank canvas waiting for information to be painted on it.
*(Teacher to draw a simple, high-frequency sine wave on the board, labelling it "Carrier Wave". Emphasise its consistent height (amplitude) and spacing (frequency).)*
``` ^ /\ /\ /\ /\ /\ /\ /\ | / \/ \/ \/ \/ \/ \/ \ Amp |/ +----------------------------> Time (High Frequency, Constant Amplitude) ``` Focal Area 2: Modulation