Lesson Notes By Weeks and Term v4 - SHS 3
APPLICATIONS OF ELECTRONICS
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APPLICATIONS OF ELECTRONICS
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Subject: Physics
Class: SHS 3
Term: 2nd Term
Week: 15
Grade code: 3.3.4.LI.2
Strand code: 3
Sub-strand code: 4
Content standard code: 3.3.4.CS.1
Indicator code: 3.3.4.LI.2
Theme: ELECTRIC FIELD, MAGNETIC FIELD AND ELECTRONICS
Subtheme: APPLICATIONS OF ELECTRONICS
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This lesson introduces the concept of rectification, focusing on the design and operation of full-wave rectifiers. In Ghana, the electricity supplied to our homes and schools by the Electricity Company of Ghana (ECG) is Alternating Current (AC). However, most of the electronic devices we use daily—our mobile phones, laptops, radios, and televisions—require Direct Current (DC) to function. A rectifier is the crucial electronic circuit that converts AC to DC. Understanding how to design a rectifier is a fundamental step into the world of practical electronics, enabling us to power the devices that are essential to modern life.
2.1. Alternating Current (AC) vs. Direct Current (DC) Alternating Current (AC): The type of electricity supplied to our homes. The direction of current flow and the voltage periodically reverse. It is represented by a sine wave. Direct Current (DC): The type of electricity required by most electronic devices. The current flows in only one direction, and the voltage is constant. It is represented by a straight line.
Rectification is the process of converting AC into DC. The electronic component that performs this task is called a rectifier. 2.2. The Key Component: The p-n Junction Diode
The hero of our rectifier circuit is the p-n junction diode. Think of it as a one-way street or a valve for electricity. It allows current to flow easily in one direction (when it is forward-biased). It blocks the flow of current in the opposite direction (when it is reverse-biased).
Symbol: The arrow in the symbol points in the direction of conventional current flow. 2.3. From Half-Wave to Full-Wave Rectification