Method for Drawing the Normal

The normal is a line perpendicular to a surface. A light ray sent perpendicularly to the surface of a mirror is reflected on itself. This property is to be used to find the normal in a mirror.

1. Place the mirror in front of the ray box on the sheet of paper.

2. Use a pencil to draw a straight line along the plane mirror to trace its reflective surface on the sheet of paper.

3. Turn on the ray box and send a ray of light towards the mirror so that the reflected ray and the incident ray overlap. This ray should be perpendicular to the mirror surface.

4. Draw a dotted line showing the position of the light ray onto the paper.

5. Remove the mirror and ray box from the paper.

6. Connect the dots of the line drawn on the sheet with the ruler. This line illustrates the normal of the plane mirror at the point of incidence.

7. Put away the equipment.

1. Place the mirror in front of the ray box on the sheet of paper.

2. Use a pencil to draw a line along the curved mirror in order to trace its reflective surface onto the paper.

3. Turn on the ray box and send a ray of light towards the mirror so that the reflected ray and the incident ray overlap.

4. Draw a dotted line showing the position of the light ray on the paper.

5. Remove the mirror and ray box from the paper.

6. Connect the dots drawn to form a line on the sheet. This line illustrates the normal of the curved mirror.

For the concave mirror

For the convex mirror

7. Put away the equipment.