Optics deals with the behaviour of light and other waves (i.e. sound)
Wavefront any spherical surface that is concentric with the point-like source.
Rays are the paths of particles. They are the radii of the spherical wave form.
Uniform Isotropic Material is a material with the same properties in all regions and all directions.
Specular is reflection at a definite angle from a very smooth surface.
Diffuse is scattered reflection from a rough surface.
The vast majority of objects in our environment are visible because their surfaces reflect light in a diffuse manner.
The law of reflection can be mathematically proved using Fermat’s principle.
This states that the path taken between two points by a way of light is the path that can be traversed in the least time.
Object (or source) is anything from which light rays can radiate.
An extended object is one that is made up of a very large number of point objects.
Image Point is where light rays appear to converge towards or divulge from.
Image Distance is the distance behind the mirror of an image point.
Virtual Image an image where the outgoing rays don’t actually pass through the image point. These are commonly observed during refraction.
Is the change in direction of a wave when it crosses a surface between materials with different optical properties.
The change in direction of a ray of light traveling through the interface between two materials.
main of Refraction, (n), is the ratio of the speed of light in vacuum to the speed in the material.
The speed of light in vacuum, (c), is 299,792,458 m/s. This is the maximum possible speed, light always travels more slowly in a material. Hence, the speed of light, (v), in a material will decrease (n) times.
We can see that refraction apparently bends light. Thus, Snell’s Law explains why a partially submerged ruler appears bent.
If light is incident at an angle where $\sin\theta_{r} > 1$, it cannot traverse across the interface but is reflected instead.
Critical Angle is the point where TIR occurs and can be easily found from Snell’s Law:
The simplest lens has two spherical surfaces close enough together that we can neglect the distance between them.
Converging Lens when rays parallel to the axis pass through it, they converge to a single point and form a real image.
Focal Length, ((f)), of a converging lens is defined as the distance from the centre of the lens that rays parallel to the optical axis cross it, forming a focal spot ((F)).
u = object distance v = image distance f = focal length
