SHS3 Physics · Semester 2 Week 3: Alternating Current

Lesson notes

Learning Objectives

Indicator: 3.3.2.LI.2 - Distinguish between the types of AC waveforms.

By the end of the lesson, learners can:

Identify and describe at least three types of AC waveforms (sinusoidal, square, triangular, and sawtooth) by their characteristic shapes and properties.
Distinguish between the waveforms by comparing their peak values, root mean square (rms) values, and the mathematical relationships that govern them.
Explain why the sinusoidal waveform is the standard form of AC supplied by the Electricity Company of Ghana (ECG) and used in homes and industries.
Relate the distinctive features of each waveform (shape, frequency, peak values) to practical applications such as signal generators, inverters, and electronic circuits.
Justify, using strategic reasoning at Depth of Knowledge Level 3, which waveform type is best suited for a given practical scenario based on its electrical characteristics.

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Curriculum details

Strand: Electric Field, Magnetic Field and Electronics (Strand 3)
Sub-strand: Alternating Current (3.2)
Content standard: 3.3.2.CS.1 - Demonstrate knowledge and understanding of Alternating Current Theory. 3.3.2.LO.1 Describe alternating current and utilise the associated mathematical relationships
Indicator: 3.3.2.LI.2 - Distinguish between the types of AC waveforms.
Suggested placement: Semester 2, Week 3 (Week 23 of the year)
Our suggestion, laid out in curriculum order across three terms of twelve weeks. NaCCA does not fix the week, so follow your school's scheme of learning.
Source document note: The official curriculum document has a fault in this entry, so the curriculum text above is transcribed exactly as printed:

indicator text - p.178: the document prints this learning indicator code as 3.3.1.LI.2
Curriculum reference: NaCCA curriculum document, p. 178

Exemplars (from the NaCCA curriculum)

Collaborative learning: Using the videos and simulation as well as internet/reference books let learners research to find the meaning of the following (i) Peak current Io, (ii) Peak voltage Vo, (iii) Root mean square value of alternating current I rms (iv) root mean square value of alternating voltage V rms terms.
Provide equitable access to resources and opportunities.
Assessment (3.3.2.AS.2). The document marks these depth-of-knowledge levels for this indicator: Level 3 Strategic reasoning.
Teaching and Learning Resources:
- Audio-visuals
- Internet
- Projectors
- YouTube
- Interactive
- Reference virtual laboratory books