Gr.10 Physics - Reflection: Plane Mirrors

Textbook: 10.2

Law of Reflection:

angle of incidence = angle of reflection

Normal

• Perpendicular to the point of incidence(vertex).

• Angles are always measured from the normal.

Image

• Reproduction of an object

• Produced by an optical device which is any technology that uses light(eg. mirror, lens)

Virtual Images

• Cannot be visually projected on a screen.

• Formed by light coming from an apparent(not real) light source.

• Always upright

• Appears behind mirror

• Images on plane mirrors are always virtual

SALT

Size: compared to the original object is it the same size?

Attitude: which way is the image oriented compared to the original object.

Location: location of the image (in front or behind mirror)

Type: is the image a real or virtual image?

Plane Mirror Images SALT

S: object size = image size

A: ALWAYS upright

L: object distance from mirror = image distance from mirror

T: virtual image —> image is reversed (left to right)

Steps for finding an image in a Plane Mirror using Ray Diagrams

1. Draw a ray from the object that strikes perpendicular to the mirror surface(a normal). The virtual ray extends into the mirror the same distance.

2. Draw a ray that strikes the mirror at any angle and reflects so the angle of incidence = the angle of reflection. Extend the virtual ray into the mirror.

3. Where these two ray meet is the part of the object that appears as a virtual image.

4. Repeat for all points of the object

Plane mirror

Mirror with a flat, reflective surface.