Waves and Light

By the end of this topic you should know:

A physical model of a transverse wave demonstrates it moves from place to place, while the material it travels through does not, and describes the properties of speed, wavelength and reflection.

When a light ray meets a different medium, some of it is absorbed and some reflected. For a mirror, the angle of incidence equals the angle of reflection. The ray model can describe the formation of an image in a mirror and how objects appear different colours.

When light enters a denser medium it bends towards the normal; when it enters a less dense medium it bends away from the normal. 

Refraction through lenses and prisms can be described using a ray diagram as a model.

Construct ray diagrams to show how light reflects off mirrors, forms images, and refracts.

Light travels at 300 million metres per second in a vacuum.

Different colours of light have different frequencies.

By the end of this topic you should be able to:

Describe the properties of different longitudinal and transverse waves.

Use the wave model to explain observations of the reflection, absorption and transmission of a wave.

Use ray diagrams of eclipses to describe what is seen by observers in different places.

Explain observations where coloured lights are mixed or objects are viewed in different lights.

Use ray diagrams to describe how light passes through lenses and transparent materials.

Describe how lenses may be used to correct vision.

By the end of this topic you should understand these key words:

Waves: Vibrations that transport energy from place to place without transporting matter.

Transverse wave: Where the direction of vibration is perpendicular to that of the wave.

Transmission: Where waves travel through a medium rather than being absorbed or reflected.

Incident ray: The incoming ray.

Reflected ray: The outgoing ray.

Normal line: From which angles are measured, at right angles to the surface.

Angle of reflection: Between the normal and reflected ray.

Angle of incidence: Between the normal and incident ray.

Refraction: Change in the direction of light going from one material into another.

Absorption: When energy is transferred from light to a material.

Scattering: When light bounces off an object in all directions.

Transparent: A material that allows all light to pass through it.

Translucent: A material that allows some light to pass through it.

Opaque: A material that allows no light to pass through it.

Convex lens: A lens that is thicker in the middle which bends light rays towards each other.

Concave lens: A lens that is thinner in the middle which spreads out light rays.

Retina: Layer at the back of the eye with light detecting cells and where image is formed.