SIMPLE EXPERIMENT: LAW OF REFLECTION

This activity investigates the rule of reflection, which focuses on obtaining, collecting, and considering evidence. The students should learn and remember the basic terms that are associated with the law of reflection.

When you look in a mirror, you can see a reflection of yourself.  If you look at texts on the newspapers or magazines, they appear to be reversed, which is the way light is reflected by a mirror. How can we investigate this phenomenon? What is reflection? What is the law of reflection?

In this practical, you need plane mirrors, concave, and convex mirrors.  Your focus is on making measurements accurately, recording the results, and making conclusions from the evidence collected.

Materials/Apparatus

• ray box
• dc-power supply (depending on the ray box)
• slit plate
• plane mirror
• concave mirror
• convex mirror
• a piece of white paper
• sharp pencil
• ruler
• protractor

Procedure

1. Place the white paper on the desk or table.
2. Put a plane, concave, or convex mirror along one of the short edges.
3. Using your pencil, draw a line on the paper along the front of the mirror.
4. Place the protractor in front of the mirror.
5. Draw a dotted line from the mirror at 90 degrees. This is your ‘Normal Line’.
6. Turn on the ray box with the single slit inserted, and aim the ray at the point where the normal line touches the mirror. ( This is the incident ray).
7. Measure the angle between the normal line and the incident ray.
8. Keeping the set-up in exactly the same place, measure the angle between the reflected ray and the normal line.
9. Repeat procedures a to h using four more different incident angles and measure their reflected angles.
10. Draw a table for your results.

Assessment

1. Describe the pattern in your results using appropriate science words.
2. State your conclusion based on the evidence collected.
3. Explain your conclusion using scientific knowledge and understanding.