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: 1st Term
Week: 1
Grade code: 2.5.2.LI.12
Strand code: 5
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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Welcome, students! Look around you at your mobile phones, the school's public address system, or the television at home. All these electronic devices need Direct Current (DC) to work. However, the power we get from the Electricity Company of Ghana (ECG) is Alternating Current (AC). How do we solve this problem? This lesson introduces the magic component that makes this conversion possible: the semiconductor diode. We will learn about its structure and how it acts as a one-way gate for electricity. We will then use this knowledge to build and understand circuits called rectifiers, which are the first and most important step in converting AC to the DC our gadgets need.
2.1. Introduction to Semiconductors and the P-N Junction Diode
An electronic component's behaviour depends on the material it's made from. Conductors (like copper) allow electricity to flow easily. Insulators (like rubber) do not allow electricity to flow. Semiconductors (like Silicon and Germanium) are special. They can be made to act as either conductors or insulators under specific conditions. This control is the key to all electronics.
To make semiconductors useful, we "dope" them, which means adding a small, calculated impurity. N-type Semiconductor: Doped so it has an excess of free electrons (Negative charge carriers). P-type Semiconductor: Doped so it has an excess of "holes," which are spaces where electrons should be (can be thought of as Positive charge carriers).
A P-N Junction Diode is created by joining a piece of P-type semiconductor material to a piece of N-type material. Structure: It has two terminals: the Anode (connected to the P-type side) and the Cathode (connected to the N-type side). Schematic Symbol: The arrow points in the direction of conventional current flow (from positive to negative). 2.2. Biasing the Diode