Physics Year 11 - Module 3 - Lesson 15

Refraction of Light, Snell's Law and Total Internal Reflection

Use this worksheet after reading the lesson to practise the key ideas and prove you can meet the success criteria.

Name

Date

Class

1. Key Ideas

Light bends when it changes speed across a boundary, and that bending can be quantified. Snell's law links the angles and refractive indices, while total internal reflection explains how optical fibres and many precision devices keep light trapped inside a medium.

What refractive index means
Why light bends when its speed changes across media

2. Success Criteria

By the end, you should be able to:

What refractive index means
Snell's law for refraction of light
The definition of critical angle

3. Key Terms

WorkThe product of force and displacement in the direction of the force; W = Fd.

EnergyThe capacity to do work, measured in joules (J).

Kinetic EnergyThe energy of motion; KE = ½mv².

Potential EnergyStored energy due to position or configuration.

PowerThe rate at which work is done or energy is transferred; P = W/t.

Conservation of EnergyThe principle that energy cannot be created or destroyed, only transformed.

4. Activity: Build the Lesson Map

Use the lesson to complete the table. Keep answers brief but specific.

Prompt	Your answer
Main concept
Important example
Common mistake to avoid
How this links to the next lesson

5. Short Answer Questions

1. 7. Explain what refractive index tells us about a medium.

Band 33 marks

2. 8. Light enters glass ($n = 1.50$) from air at an incidence angle of 30°. Find the refraction angle.

Band 43 marks

3. 9. Define total internal reflection and state the two conditions required for it to occur.

Band 54 marks

6. Extend: Apply the Idea

Band 5/65 marks

A student gives a memorised answer about Refraction of Light, Snell's Law and Total Internal Reflection but does not use evidence or reasoning.

Improve the answer by writing a stronger response that uses accurate terminology, a relevant example and a clear explanation.

7. Multiple Choice

1. What is the best first step when answering a question about Refraction of Light, Snell's Law and Total Internal Reflection?

A. Identify the key concept being tested

B. Write every fact from memory

C. Ignore the command word

D. Skip examples and evidence

2. Which answer would show stronger understanding of Refraction of Light, Snell's Law and Total Internal Reflection?

A. An answer with accurate terms and reasoning

B. A copied definition only

C. A single-word response

D. An answer with no example

3. What should you do if a question asks you to explain?

A. Link the idea to a reason or cause

B. List unrelated facts

C. Only draw a diagram

D. Write the shortest possible answer

8. Success Criteria Proof

Finish with evidence that you can do each success criterion.

Success criterion 1

Prove that you can: What refractive index means

Band 32 marks

Success criterion 2

Prove that you can: Snell's law for refraction of light