Ray Diagram Practice Worksheet : Three Light Sources

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LAB – Reflection and Mirrors

Name: ______Date: ______Block: ______

Introduction: We can see our face in the mirror because mirrors are very smooth and shiny. Light bounces, or reflects, off the smooth and shiny surface so that we can see an image. Light reflects from a mirror at the same angle as it arrives.

Purpose: To determine how plane mirrors reflect light in different situations.

Materials:  Plane mirror  Ray box and baffle  Paper – white, black, aluminum foil  Ruler and pencil Part A – Incident Angle Equals Reflected Angle

1. Place the plane mirror on the next page where it says mirror. 2. Place a single-slit baffle into the ray box and shine a light ray along the 90-degree angle of the protractor to the mirror’s surface (NOTE: try to shine the light so that it will always hit “Light should shine here” spot). This will be the normal. Draw and label this line. 3. Move the ray box to different positions so that the incident light ray strikes the mirror at different angles each time. On the paper, use a pencil and ruler to trace the incident ray and the reflected ray of light produced in each position. Do the exercise for the following angles of incident: 70o, 45o, 25o, and 5o. Label each pair of light rays with the corresponding numbers and use arrows to indicate the direction of the light rays.

Diagram for Part A:

Mirror

* Light should shine here

Part A Questions

1. What happened to the reflected ray of light when it was shone along the 90o angle of the protractor?

2. Describe what happened to the angle of the reflected light ray as the angle of the incident light ray becomes larger. Part B – Reflections Off Different Objects

1. Insert a three-slit baffle into your ray box. 2. Place the mirror on the black line of your lab sheet. 3. Shine the light rays at the mirror at about a 45o angle. Draw the lines of light for both the incident and reflected rays. Also, label both lines and draw arrows indicating the direction light is traveling. 4. Repeat steps 2 and 3 using the following items instead of a plane mirror: a crumpled piece of aluminum foil, a white piece of paper, and a black piece of paper.

Diagrams for Part B:

Mirror

Aluminum Foil White Paper

Black Paper

Part B Questions

1. At what angle do the light rays appear to be coming out of the mirror? What are these rays of light called?

2. What did you notice when you shone light on the aluminum foil? What type of reflection can this be considered?

3. Why do you think that there was some reflection off of the white piece of paper, but none off of the black piece of paper?

4. Movie screens must be diffuse reflectors. Why do you think polished glass mirrors are not used as screens? Part C – Reflections Off a Convex Mirror

1. Insert a five-slit baffle into your ray box. 2. Place the convex mirror on the black line of your lab sheet. 3. Shine the light rays at the mirror at a 90o angle. Make sure that the center beam of light hits the center of the mirror. 4. Draw the light rays entering and leaving the mirror in two different colours. Label the incident rays and reflected rays. 5. Repeat steps 2-4, but have the incident ray coming in at a 45o angle.

Diagrams for Part C:

Convex Mirror

90o angle incident ray

Convex Mirror

Part C Questions 1. What is the shape of a convex mirror?

2. Did the reflected rays converge or diverge when light was shone at the convex mirror?

3. How do the reflected rays from the convex mirror differ from those reflected off of the plane mirror? Why?

Part D – Reflections Off a Concave Mirror

1. Insert a five-slit baffle into your ray box. 2. Place the concave mirror on the black line of your lab sheet. 3. Shine the light rays at the mirror at a 90o angle. Make sure that the center beam of light hits the center of the mirror. 4. Draw the light rays entering and leaving the mirror in two different colours. Label the incident rays and reflected rays. 5. Repeat steps 2-4, but have the incident ray coming in at a 45o angle.

Diagrams for Part D:

Concave Mirror

Part D Questions 1. What is the shape of the concave mirror?

2. Did the reflected rays converge or diverge when light was shone at the concave mirror?

3. How do the reflected rays from the concave mirror differ from those reflected off of the plane mirror and off a convex mirror? Why?