Lesson Notes By Weeks and Term v4 - SHS 3
ALTERNATING CURRENT
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ALTERNATING CURRENT
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Subject: Physics
Class: SHS 3
Term: 2nd Term
Week: 6
Grade code: 3.3.2.LI.3
Strand code: 3
Sub-strand code: 2
Content standard code: 3.3.2.CS.1
Indicator code: 3.3.2.LI.3
Theme: ELECTRIC FIELD, MAGNETIC FIELD AND ELECTRONICS
Subtheme: ALTERNATING CURRENT
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This lesson introduces the fundamental concepts of Alternating Current (AC), the type of electricity that powers our homes, schools, and communities across Ghana, delivered by the Electricity Company of Ghana (ECG). Unlike Direct Current (DC) from batteries, AC periodically reverses direction. Understanding AC is crucial for comprehending how most electrical appliances work, from the fan in the classroom to the television at home, and how electricity is transmitted efficiently over long distances from power stations like the Akosombo Dam.
A. What is Alternating Current (AC)?
Imagine water flowing in a pipe. Direct Current (DC) is like water flowing steadily in *one direction only*. This is what you get from a battery. Alternating Current (AC) is like the water being rapidly pushed forward and then pulled backward, over and over again. The electrons in the wire move back and forth about a fixed position.
This periodic change in direction and magnitude can be represented graphically by a sine wave. B. Mathematical Definition of AC and Alternating Voltage
Because AC varies sinusoidally with time, we use the sine function to describe it. Alternating Current (I): The instantaneous current `I` (the current at any specific moment in time `t`) is given by the equation: