Refraction

REFLECTION TO REFRACTION — WORKSHEET

REFLECTION (RECAP)

Reflection occurs when light hits a surface and bounces back instead of passing through it.

REFLECTION (RECAP)

1. What is reflection?
   Reflection is when light bounces off a surface and stays in the same material.

2. What is the normal line used for?
   The normal is used as a reference line to measure angles.

3. State the law of reflection.
   The angle of incidence equals the angle of reflection.

4. Why does light bounce off a mirror instead of passing through it?
   Because the mirror surface reflects the light rather than allowing it to pass through.

UNDERSTANDING QUESTIONS

1. What is refraction?
   Refraction is the bending of light when it passes from one material into another.

2. How is refraction different from reflection?
   In reflection light bounces off a surface; in refraction light enters a new material and changes direction.

3. Name two transparent materials.
   Glass and water. (Also acceptable: clear plastic, air.)

4. What is meant by a boundary between materials?
   The surface where two different materials meet.

5. What is a refracted ray?
   A refracted ray is a light ray that has entered a new material and changed direction.

APPLY YOUR KNOWLEDGE

1. Why does a pencil appear bent in water?
   Light changes direction as it moves from water into air, so the pencil appears in a different position.

2. Why must light change direction inside a lens?
   Because lenses use refraction to focus light so images can be seen clearly.

3. Why would refraction not happen if light stayed in only one material?
   Because refraction only occurs when light passes between different materials.

CHALLENGE

1. What happens when light moves from water back into air?
   The light changes direction again and bends away from the normal.

Key ideas from last lesson:

• Incident ray — the incoming light ray.

• Reflected ray — the ray that leaves the surface.

• Normal — an imaginary line drawn at 90° to the surface where the light hits.

• Angle of incidence — the angle between the incident ray and the normal.

• Angle of reflection — the angle between the reflected ray and the normal.

LAW OF REFLECTION:

The angle of incidence equals the angle of reflection.

RECAP QUESTIONS

1. What is reflection?

1. What is the normal line used for?

1. State the law of reflection.

1. Why does light bounce off a mirror instead of passing through it?

LESSON OBJECTIVES

• Describe refraction.

• Explain how refraction differs from reflection.

• Learn key scientific vocabulary.

• Apply refraction to real situations.

KEY WORDS AND DEFINITIONS

REFRACTION — the bending of light when it passes from one material into another.

TRANSPARENT MATERIAL — a material that allows light to pass through it.

BOUNDARY — the surface where two different materials meet.

NORMAL — an imaginary line drawn at 90° to a surface at the point where light hits.

INCIDENT RAY — the incoming ray of light approaching a surface.

REFRACTED RAY — the ray of light after it enters a new material and changes direction.

INTRODUCING REFRACTION

In reflection, light stays in the same material and bounces back.

In refraction, light enters a different material such as glass, water or clear plastic. When this happens, the direction of the light ray can change.

UNDERSTANDING QUESTIONS

1. What is refraction?

1. How is refraction different from reflection?

1. Name two transparent materials.

1. What is meant by a boundary between materials?

2. What is a refracted ray?

APPLY YOUR KNOWLEDGE

1. A pencil placed in water appears bent.
   Explain what happens to the light to cause this effect.

2. Glasses help people see clearly. Why must light change direction inside a lens?

3. Why would refraction not happen if light stayed in only one material?

CHALLENGE

Predict what might happen to light if it moved from water back into air.

EFLECTION TO REFRACTION — ANSWERS

REFLECTION (RECAP)

1. What is reflection?
   Reflection is when light bounces off a surface and stays in the same material.

2. What is the normal line used for?
   The normal is used as a reference line to measure angles.

3. State the law of reflection.
   The angle of incidence equals the angle of reflection.

4. Why does light bounce off a mirror instead of passing through it?
   Because the mirror surface reflects the light rather than allowing it to pass through.

UNDERSTANDING QUESTIONS

1. What is refraction?
   Refraction is the bending of light when it passes from one material into another.

2. How is refraction different from reflection?
   In reflection light bounces off a surface; in refraction light enters a new material and changes direction.

3. Name two transparent materials.
   Glass and water. (Also acceptable: clear plastic, air.)

4. What is meant by a boundary between materials?
   The surface where two different materials meet.

5. What is a refracted ray?
   A refracted ray is a light ray that has entered a new material and changed direction.

APPLY YOUR KNOWLEDGE

1. Why does a pencil appear bent in water?
   Light changes direction as it moves from water into air, so the pencil appears in a different position.

2. Why must light change direction inside a lens?
   Because lenses use refraction to focus light so images can be seen clearly.

3. Why would refraction not happen if light stayed in only one material?
   Because refraction only occurs when light passes between different materials.

CHALLENGE

1. What happens when light moves from water back into air?
   The light changes direction again and bends away from the normal.

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