Reflection

What is the incident ray?

The light ray going towards the surface.

What is the reflected ray?

The light ray going away from the surface after reflection.

What is the normal?

The perpendicular line to the surface at the point of incidence.

What is the point of incidence?

The point where the incident ray strikes the surface.

What is the angle of incidence (i)?

The angle between the incident ray and the normal.

What is the angle of reflection (r)?

The angle between the reflected ray and the normal.

Define regular (specular) reflection.

Reflection from a smooth surface where parallel incident rays remain parallel after reflection.

Define diffuse reflection.

Reflection from a rough surface where parallel incident rays scatter in different directions.

State the first law of reflection.

The incident ray, reflected ray, and normal at the point of incidence all lie in the same plane.

State the second law of reflection.

The angle of incidence equals the angle of reflection.

How do you construct a normal on a curved mirror?

Draw a tangent at the point of incidence, then construct a perpendicular to it.

Steps to draw image of a point object in a plane mirror?

(1) Extend a perpendicular line into mirror, making image as far behind as object is in front.
(2) Draw reflected rays from mirror to eye.
(3) Draw incident rays from object to mirror.

How do you show virtual rays in a diagram?

Use dotted lines behind the mirror.

What are the characteristics of an image in a plane mirror?

Same size, upright, laterally inverted, same distance behind mirror, virtual.

What is a virtual image?

An image formed when light rays appear to meet but do not actually meet (cannot be captured on screen).

What image is formed in a concave mirror when the object is inside the focal length (F)?

Virtual, upright, larger than the object.

What image is formed in a convex mirror for any object position?

Virtual, upright, diminished.

Why are convex mirrors used as vehicle side mirrors?

They provide a wide field of view but form diminished images.

Why are concave mirrors used by dentists?

They form magnified, upright images when object is close.

Why can’t you capture a virtual image on a screen?

Because light rays do not actually converge at the image position.

What is the direction of light in ray diagrams?

Always object → mirror → eye.