Lesson Notes By Weeks and Term v4 - SHS 3
ELECTRONIC COMPONENTS AND CIRCUITS
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ELECTRONIC COMPONENTS AND CIRCUITS
Download the Lessonotes Mobile Ghana app for faster lesson access on Android and iPhone.
Subject: Applied Technology
Class: SHS 3
Term: 2nd Term
Week: 20
Grade code: 2.5.2.LI.12
Strand code: 4
Sub-strand code: 2
Content standard code: 2.5.2.CS.1
Indicator code: 2.5.2.LI.12
Theme: ELECTRICAL AND ELECTRONIC TECHNOLOGY
Subtheme: ELECTRONIC COMPONENTS AND CIRCUITS
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Radio is a part of our daily lives in Ghana. From listening to the morning news on Peace FM, enjoying music on Joy FM, or following community announcements on a local station in our hometown, we are constantly interacting with radio waves. But have you ever wondered how the voice of the presenter or the sound of the music travels from the radio station and comes out of your radio's speaker? This lesson will demystify that process. We will explore the two main types of radio broadcasting we use, AM (Amplitude Modulation) and FM (Frequency Modulation), and understand the electronic circuits inside a radio that make this "magic" happen.
A. The Foundation: What is Modulation?
Before we can understand a radio *receiver*, we must first understand what it is trying to receive. The audio we want to hear (like a person's voice or music) is a low-frequency signal. It cannot travel very far on its own. To send it over long distances, we "piggyback" it onto a high-frequency radio wave, called a carrier wave. This process of combining the information signal with the carrier wave is called Modulation.
Imagine you want to send a letter (your information) from Accra to Tamale. You can't just throw the letter into the air. You put it in a fast bus (the carrier wave) that is already going to Tamale. Modulation is the process of putting the letter on the bus.
There are two main ways to do this: Amplitude Modulation (AM) In AM, the amplitude (strength or height) of the high-frequency carrier wave is changed in accordance with the information signal (the audio). The frequency of the carrier wave remains constant. Carrier Wave: A constant high-frequency, constant amplitude wave. Information Signal (Audio): The voice or music we want to send. AM Wave: The carrier wave's amplitude now mirrors the shape of the audio signal.