Lesson Notes By Weeks and Term v4 - SHS 2
ELECTROMAGNETISM
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ELECTROMAGNETISM
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Subject: Physics
Class: SHS 2
Term: 2nd Term
Week: 9
Grade code: 2.3.2.LI.4
Strand code: 3
Sub-strand code: 2
Content standard code: 2.3.2.CS.2
Indicator code: 2.3.2.LI.4
Theme: ELECTRIC FIELD, MAGNETIC FIELD AND ELECTRONICS
Subtheme: ELECTROMAGNETISM
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This lesson introduces the fascinating world of electromagnetism, the fundamental principle that connects electricity and magnetism. We often think of them as separate forces, but they are two sides of the same coin. This connection is the basis for countless technologies we use every day in Ghana – from the electric motor in a fan that cools us down, to the generator that provides light during a power outage ('dumsor'), and the speakers that play our favourite highlife and afrobeats music. By understanding how an electric current can create a magnet, we unlock the secrets behind some of the most important inventions in modern life.
Concept 1: Oersted's Discovery - The Link Between Electricity and Magnetism
In 1820, a physicist named Hans Christian Oersted was giving a lecture. He had a wire connected to a battery and a magnetic compass nearby. He noticed that every time he switched on the current in the wire, the needle of the compass deflected (moved). When he switched the current off, the needle returned to its original North-South position.
This was a groundbreaking discovery! It was the first time anyone had shown a direct link between electricity and magnetism.
Oersted's Conclusion: An electric current produces a magnetic field. A moving electric charge creates a magnetic field in the space around it. Concept 2: Magnetic Field around a Straight Current-Carrying Wire