Year 7 Science · Unit 3 · Lesson 15
Challenge Worksheet
Learning Goals
Design a mini-experiment
A scientist asks: "Does the angle of incidence always equal the angle of reflection, regardless of which type of mirror surface is used?" Plan the investigation below.
| What I will change (independent variable) | |
| What I will keep the same (controlled variables — list at least 3) | |
| What I will measure (dependent variable) | |
| My prediction (including which surfaces I expect will follow the law) | |
| Equipment needed | |
| How I would know if my prediction is wrong | |
| One limitation of this experiment |
Would this experiment be able to distinguish between specular and diffuse reflection? Explain how your results would differ for each surface type, and what this would tell you about the law of reflection.
1. Australia's National Broadband Network (NBN) uses optical fibres to carry internet signals. A physics student says: "Optical fibres use refraction to keep light inside the cable — that's why we don't need metal wires anymore." Evaluate this claim. Is the student's explanation of the physics correct? What is the actual principle keeping light inside optical fibres, and how does it relate to refraction?
2. Explain why the sky appears blue and sunsets appear red and orange. Your explanation must reference the ray model of light and describe what happens to light as it travels through Earth's atmosphere at different times of day. (Hint: short wavelengths scatter more than long wavelengths.)
Wrap Up
In one sentence, what was the main idea of this lesson?