| Term | Definition |
|---|---|
| angle of incidence | The angle between an incident ray and the normal to a surface. |
| angle of reflection | The angle between a reflected ray and the normal to a surface. |
| coherent | Describing light waves that maintain a constant phase relationship, as produced by a laser. |
| diffraction | The spreading of a wave around the edges of an obstacle or through an opening. |
| diffuse reflection | The reflection of light from a rough surface that scatters light in many different directions due to varying surface normals. |
| geometric optics | The study of light behavior using ray diagrams, where the wave nature of light can be neglected. |
| incident ray | A ray of light traveling toward and striking a surface. |
| interference | The phenomenon where the wave nature of light is important and cannot be neglected, involving the superposition of light waves. |
| law of reflection | The principle stating that the angle of incidence equals the angle of reflection, both measured from the normal to the surface. |
| light ray | A straight line that is perpendicular to the wavefront of a light wave and points in the direction of travel of the wave. |
| monochromatic | Light consisting of a single wavelength or frequency, as produced by a laser. |
| normal | An imaginary line perpendicular to a surface at the point where a light ray strikes it. |
| ray diagram | A diagram that depicts the path of light before and after an interaction with matter. |
| reflected ray | A ray of light that bounces off a surface after reflection. |
| reflection | The bouncing of light off a surface back into the medium from which it came. |
| rough surface | A surface with irregularities that cause diffuse reflection of light. |
| smooth surface | A surface with minimal irregularities that causes specular reflection of light. |
| specular reflection | The reflection of light from a smooth surface that reflects light uniformly in a single direction due to a constant surface normal. |
| wavefront | A surface of constant phase in a propagating wave, perpendicular to the direction of wave propagation. |
| Term | Definition |
|---|---|
| center of curvature | The center point of the sphere from which a spherical mirror is curved, located on the principal axis at a distance equal to twice the focal length. |
| concave mirror | A converging mirror with a curved surface that reflects inward, causing parallel light rays to converge at a focal point. |
| convex mirror | A diverging mirror with a curved surface that reflects outward, causing parallel light rays to appear to diverge from a focal point behind the mirror. |
| focal length | The distance from the mirror's surface to its focal point, which determines the location of images formed by the mirror. |
| focal point | The point where reflected light rays converge (for concave mirrors) or appear to originate (for convex and plane mirrors). |
| inverted image | An image that is flipped relative to the object's orientation. |
| magnification | The ratio of the size of an image produced by a mirror to the size of the object, indicating whether the image is enlarged, reduced, or the same size. |
| plane mirror | A flat mirror that reflects light rays such that the focal point is located at an infinite distance from the mirror. |
| principal axis | The line passing through the center of a mirror perpendicular to its surface, used as a reference for describing light ray behavior. |
| principal rays | Three specific light rays used in ray diagrams: the ray parallel to the principal axis, the ray reflecting at the center of the mirror, and the ray passing through the focal point. |
| ray diagram | A diagram that depicts the path of light before and after an interaction with matter. |
| real image | An image formed when reflected light rays from a common point intersect at another common point, which can be projected onto a screen. |
| sign conventions | A system of rules used to determine the signs of distances and other quantities relative to the mirror's position and orientation. |
| upright image | An image that has the same orientation as the object. |
| virtual image | An image formed when reflected light rays diverge such that they appear to have originated from a common point behind the mirror. |
| Term | Definition |
|---|---|
| angle of incidence | The angle between an incident ray and the normal to a surface. |
| angle of refraction | The angle between a refracted light ray and the normal to a surface. |
| critical angle | The minimum angle of incidence at which total internal reflection occurs when light travels from a medium with higher index of refraction to one with lower index of refraction. |
| index of refraction | A measure of how much a medium slows down light compared to its speed in vacuum, determining the degree of bending and reflection of light at interfaces. |
| normal | An imaginary line perpendicular to a surface at the point where a light ray strikes it. |
| refraction | The change in direction of a light ray as it passes from one medium into another. |
| Snell's law | The law relating the angles of incidence and refraction of a light ray passing between two media to their respective indices of refraction, expressed as n₁ sin θ₁ = n₂ sin θ₂. |
| total internal reflection | The complete reflection of light back into a medium when light traveling from a denser medium strikes the boundary with a less dense medium at an angle greater than the critical angle. |
| Term | Definition |
|---|---|
| concave lens | A lens that curves inward and causes parallel light rays to diverge as if they originated from a focal point. |
| convex lens | A lens that curves outward on both sides and converges parallel light rays toward a focal point. |
| focal length | The distance from the mirror's surface to its focal point, which determines the location of images formed by the mirror. |
| focal point | The point where reflected light rays converge (for concave mirrors) or appear to originate (for convex and plane mirrors). |
| inverted image | An image that is flipped relative to the object's orientation. |
| magnification | The ratio of the size of an image produced by a mirror to the size of the object, indicating whether the image is enlarged, reduced, or the same size. |
| principal axis | The line passing through the center of a mirror perpendicular to its surface, used as a reference for describing light ray behavior. |
| principal rays | Three specific light rays used in ray diagrams: the ray parallel to the principal axis, the ray reflecting at the center of the mirror, and the ray passing through the focal point. |
| ray diagram | A diagram that depicts the path of light before and after an interaction with matter. |
| real image | An image formed when reflected light rays from a common point intersect at another common point, which can be projected onto a screen. |
| sign conventions | A system of rules used to determine the signs of distances and other quantities relative to the mirror's position and orientation. |
| thin lens | A lens whose thickness is negligible compared to its focal length, allowing the use of simplified equations to describe image formation. |
| thin-lens equation | The equation 1/s_i + 1/s_o = 1/f that relates the image distance, object distance, and focal length of a thin lens. |
| upright image | An image that has the same orientation as the object. |
| virtual image | An image formed when reflected light rays diverge such that they appear to have originated from a common point behind the mirror. |