Waves · SHS1 Physics

Lesson notes

Learning Objectives

Indicator: 1.2.2.LI.2 - Determine the refractive index of a medium.

By the end of the lesson, learners can:

Define refractive index as the ratio of the sine of the angle of incidence to the sine of the angle of refraction when light travels from air into a medium.
Set up and carry out an experiment using a rectangular glass prism to measure angles of incidence and refraction.
Calculate the refractive index of a glass prism from measured values of sin i and sin r using the formula n = sin i / sin r.
Determine the refractive index of a medium from a graph of sin i against sin r and interpret the slope.
Justify the need to take multiple readings and average them to improve the accuracy of a determined refractive index.

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Curriculum details

Strand: Energy (Strand 2)
Sub-strand: Waves (2.2)
Content standard: 1.2.2.CS.3 - Demonstrate knowledge and understanding of refraction. 1.2.2.LO.3 Explain refraction and recognise its relevance in different media.
Indicator: 1.2.2.LI.2 - Determine the refractive index of a medium.
Suggested placement: Semester 2, Week 2 (Week 22 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. 56

Exemplars (from the NaCCA curriculum)

Think-pair-share: With the materials provided set up experiment for students to determine the refractive index of a rectangular prism. Exemplars
- Determine sin i, sin r, i = angle of incidence r = angle of refraction.
- Determine the ratio of sin i to sin r
Encourage the appreciation and valuing of the skills and abilities of individuals from diverse backgrounds, including gender, race, ethnicity, socioeconomic status, and disabilities.
Assessment (1.2.2.AS.2). The document marks these depth-of-knowledge levels for this indicator: Level 3 Strategic reasoning.
Teaching and Learning Resources:
- Bowl/ basin
- Stick
- audio-visual
- internet projectors
- Interactive virtual laboratory