Wave · SHS3 Physics

Lesson notes

Learning Objectives

Indicator: 3.2.2.LI.3 - Calculate the image distance and the magnification using the lens formula.

By the end of the lesson, learners can:

State the lens formula as 1/f = 1/u + 1/v and correctly identify the symbols f, u, and v.
Apply the Cartesian sign convention to assign positive and negative signs to object distance, image distance, and focal length in lens problems.
Calculate the image distance (v) when given the focal length (f) and object distance (u) for both converging and diverging lenses.
Calculate the magnification (M) of a lens using both the formula M = v/u and the alternative form M = image height / object height.
Determine the characteristics of the image (real or virtual, magnified or diminished, erect or inverted) from the sign and magnitude of the calculated values, and use these to explain how optical instruments such as a camera and a projector work.

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Curriculum details

Strand: Energy (Strand 2)
Sub-strand: Wave (2.2)
Content standard: 3.2.2.CS.1 - Demonstrate knowledge and understanding of lenses 3.2.2.LO.1 Use the working principles of lenses to explain the operation of some optical instruments.
Indicator: 3.2.2.LI.3 - Calculate the image distance and the magnification using the lens formula.
Suggested placement: Semester 1, Week 16 (Week 16 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.
Curriculum reference: NaCCA curriculum document, p. 167

Exemplars (from the NaCCA curriculum)

Experiential learning: Let learners use the lens formula to determine image position, magnification and characteristics i.e., Real is positive and cartesian convention.
Recognise diverse talents and perspectives.
Assessment (3.2.2.AS.3). The document marks these depth-of-knowledge levels for this indicator: Level 2 Skills of conceptual understanding; Level 3 Strategic reasoning.
Teaching and Learning Resources:
- Audio-visuals
- Internet
- Projectors
- YouTube
- Interactive
- Reference virtual laboratory books