Optics - Science Olympiad 2025

Reflection

the throwing back by a body or surface of light, heat, or sound without absorbing it

Refraction

the fact or phenomenon of light, radio waves, etc. being deflected in passing obliquely through the interface between one medium and another or through a medium of varying density

Specular reflection

bending of light as it passes through a smooth surface, photography, vision correction, and optical instruments, can cause shimmering or glare, or a clear reflection

Law of Reflection

The law of reflection states that the angles of an incident ray and reflected ray are the same as each other and are in the same plane as the normal

Index of refraction

Ratio of the speed of light in vacuum to that in the medium

Snell's law

a law stating that the ratio of the sines of the angles of incidence and refraction of a wave are constant when it passes between two given media

Critical angle

the angle of incidence beyond which rays of light passing through a denser medium to the surface of a less dense medium are no longer refracted but totally reflected

Prisms

Transparent optical element with flat, polished surfaces that refract light, reflects light without focusing

Mirrors

A mirror is a reflective surface that does not allow the passage of light and instead bounces it off, thus producing an image

Lenses

A lens is a transmissive optical device that focuses or disperses a light beam by means of refraction

Convex lens

A Convex lens is a converging lens that brings incident light rays together at a point

Concave lens

A concave lens is thinner at its center and thicker at its edges, curving inward to create a hollow or dented appearance, "diverging lens" because it spreads out parallel rays of light that pass through it, used in glasses for nearsidedness.

Plain mirrors

For plane mirrors, the reflected image (a virtual image) and object are along the same line, perpendicular to the reflective surface. The image and object are equidistant from the mirror.

Ray tracing

Ray tracing is the technique of determining or following (tracing) the paths that light rays take. Experiments, as well as our own experiences, show that when light interacts with objects several times as large as its wavelength, it travels in straight lines and acts like a ray.

Focal length

The focal length of an optical system is a measure of how strongly the system converges or diverges light; it is the inverse of the system's optical power. A positive focal length indicates that a system converges light, while a negative focal length indicates that the system diverges light.

Virtual object

A point at which incident light rays (as seen from the mirror) appear to converge is said to be a virtual object. In other words if the incident rays are converging, then the point of convergence is the position of virtual object.

Erect object

In optics, an erect image is one that appears right-side up. An image is formed when rays from a point on the original object meet again after passing through an optical system. In an erect image, directions are the same as those in the object, in contrast to an inverted image.

Inverted objects

Image, whose up-side down is called inverted image such as the image in the concave side of a shiny spoon.

Images and magnification

Magnification is the process of enlarging the apparent size, not physical size, of something. This enlargement is quantified by a size ratio called optical magnification. When this number is less than one, it refers to a reduction in size, sometimes called de-magnification.

Additive color theory

Additive color works by mixing colors of light. The more colors of light you add together, the closer you get to white light. It is the opposite of the color spectrum, where white light is refracted (broken up) into a rainbow of colors.

Additive primary colors

are Red, Green and Blue (RGB). These are the colors from which all other colors of light are made. You can see evidence of this on your computers, televisions and mobile phones.

Subtractive color theory

Subtractive color involves mixing physical materials like paint pigments, printing inks, and dyes. The more color materials you mix, the darker the color gets. It's called 'subtractive' because of the absorption or subtraction of certain wavelengths from white light.

Absorption

is based on how different atoms behave when light hits them.

Reflection

certain wavelengths of light are reflected off an object while other wavelengths are absorbed. The wavelengths that are reflected determine what color our eyes perceive.