Optics Terms
Convex, Converging Lens
These lenses are thicker in the middle than at the edges, such that when parallel light rays hit the lens the light is bent together, converging them, on the other side of the lens.Concave, Converging Mirror
The inside of a spoon. A way to remember which mirror is concave is that the surface of concave mirrors "cave" in. This causes it to bring light together, or in fancy physics speak, it converges light rays.Concave, Diverging Lens
These lenses are thicker at their edges and thinner in the center. Concave lenses take parallel rays of light and spread them outward away from each other so that the rays are further apart on the other side of the lens.Constructive Interference
Interacting waves that come together in phase, and combine (add) to form a bigger wave.Convex, Diverging Mirror
Convex mirrors are mirrors whose surface bulges out at us. These types of mirrors spread out, or diverge, parallel light rays that hit their surface. What results is always a virtual image that is reduced in size.Destructive Interference
Waves which come together in such a way that they cancel each other out by adding a wave crest to a wave trough. Surfers call this "a major bummer."Diffraction
The spread of a beam of light after passing through a narrow slit or bending around an opaque edge.Electromagnetic Spectrum
The entire range of wavelengths of light. Light is a wave (and a particle, too. It's special). We can only see a tiny fraction of the possible wavelengths of electromagnetic rays, but we still use them all. UV waves give us sunburns, microwaves give us dinner, and radio waves give us music.Geometric Optics
The model considering light as being made up of bajjillions of tiny particles—little balls bouncing minding their own business, obeying Newton's laws of mechanics. They're called photons, for the record.Huygens' Principle
In essence, a wave front consists of an infinite number of points. Each of these points acts as the point source of a new wave. The sum of all of these point-source wavelets gives us a brand-spanking new wave front, or a "secondary" wave front.Image Distance, di
The distance between a mirror or lens and the image (not object). Image distances are negative for virtual images and positive for real imagesImage Height, hi
The height of the image formed by a mirror or a lens. An image height is considered positive if it has the same orientation as the object and negative if it is upside down.Index Of Refraction, n
The index of refraction, n, tells us something about how light moves through that object. It is a measure of how much slower light travels through a given material than when it travels through a vacuumInterference
That football foul. Oh, not that kind. Interference happens when two of the same kind of waves (light, sound, oceanic) interact with each other.Magnification, m
The ratio of the height of the "image" object, hi, to the height of the real object, ho, or
Mirror Equation
The mirror equation relates object distance, do, and image distance, di, to the focal distance, f, of a mirror: