Chap 11.4, 11.6, 11.7 - Nelson Science 10

Light ray

Light ray

A line on a diagram representing the direction and path that light is travelling

Geometric optics

The use of light rays to determine how light behaves when it strikes objects

Incident light

Light emitted from a source that strikes an object

Transparent

When a material transmits all or almost all incident lights; objects can be clearly seen through the material (e.g. clear glass)

Translucent

When a material transmits some incident light but absorbs or reflects the rest; objects are not clearly seen through the material (e.g. frosted glass)

Opaque

When a material does not transmit any incident light; all incident light is either absorbed or reflected; objects behind the material cannot be seen at all (e.g. cardboard)

Image

Reproduction of an object through the use of light

Mirror

Any polished surface reflecting an image

Reflection

The bouncing back of light from a surface

Describe the layers of mirrors

Mirrors consist of 2 parts: front part is a sheet of glass and the back part is a thin layer of reflective silver or aluminum.

• The symbol used in physics to represent a mirror refers only to the reflective thin film

Incident ray

The incoming ray that strikes a surface

Reflected ray

The ray that bounces off a reflective surface

Normal

The perpendicular line to a mirror surface

Perpendicular

At right angles

Angle of Incidence

The angle between the incident ray and the normal

Angle of Reflection

The angle between the reflected ray and the normal

The 2 laws of reflection

1. Angle of incidence = angle of reflection

2. The incident ray, the reflected ray, and the normal all lie in the same plane

Specular reflection

• Reflection of light off a smooth surface

• A series of parallel incident rays that strike a smooth surface will have identical angles of incidence (meaning that angles of reflection will all be identical and reflected rays will all be parallel to each other)

Diffuse reflection

Reflection of light off an irregular or dull surface

• Reflected rays would be scattered in many different directions

Virtual image

An image formed by light coming from an apparent light source; light is not arriving at or coming from the actual image location.

(Appears behind the mirror)

Lateral inversion

The orientation of an image in a plane mirror that is backwards and in reverse order

What does the acronym SALT mean?

1. Size of image (compared to the object: same size, smaller, or larger)

2. Attitude of image (which way the image is oriented compared to the object: upright or inverted)

3. Location of image

4. Type of image (real or virtual). A real image is an image formed where light is actually arriving at the same location.

Describe an image in a plane mirror using SALT

An image in a plane mirror is always the same size as the object (size), upright by laterally inverted (attitude), behind the mirror and the same distance behind as the object is in front (location), and virtual (type).