Properties of Light

Each list begins with basic conceptual vocabulary you need to know for MCAT questions and proceeds to advanced terms that might appear in context in MCAT passages. The terms are links to Wikipedia articles.
Light is electromagnetic radiation.
Reflection is the change in direction of a wave front at an interface between two dissimilar media so that the wave front returns into the medium from which it originated.
Electromagnetic spectrum
The electromagnetic spectrum is the range of all possible electromagnetic radiation.
Visible spectrum
The visible spectrum is the portion of the electromagnetic spectrum that can be detected by the human eye.
Infrared radiation is electromagnetic radiation of a wavelength longer than that of visible light, but shorter than that of radio waves. The name means below red.
Ultraviolet light is electromagnetic radiation with a wavelength shorter than that of visible light, but longer than soft X-rays.
X-rays are a form of electromagnetic radiation with a wavelength in the range of 10 to 0.01 nanometers. They are a form of ionizing radiation.
Gamma ray
Gamma rays are forms of electromagnetic radiation or light emissions of a specific frequency produced from sub-atomic particle interaction, such as electron-positron annihilation and radioactive decay.
Refraction is the change in direction of a wave due to a change in its speed.
Angle of incidence
The angle of incidence is a measure of deviation of a ray to a surface from straight on.
Diffuse reflection
Diffuse reflection is the reflection of light from an uneven or granular surface such that an incident ray is seemingly reflected at a number of angles.
Radio waves
Radio waves are electromagnetic waves occurring within the portion of the electromagnetic spectrum which is a lower frequency than infrared radiation.
Refractive index
The refractive index of a medium is a measure for how much the speed of light is reduced inside the medium.
Snell's law
Snell's law is a formula used to describe the relationship between the angles of incidence and refraction for waves passing through a boundary between two different isotropic media.
Specular reflection
Specular reflection is the perfect, mirror-like reflection of light from a surface, in which light from a single incoming direction is reflected into a single outgoing direction.
Microwaves are a subcategory of radio waves with wavelengths shorter than one meter and longer than one millimeter.
Total internal reflection
Total internal reflection is an optical phenomenon that occurs when a ray of light strikes a medium boundary at an angle larger than the critical angle with respect to the normal to the surface.
Dispersion is the phenomenon that the phase velocity of a wave depends on its frequency.
Optical fiber
An optical fiber is a glass or plastic strand of material designed to guide light along its length.
A laser is a device that produces coherent radiation, typically in the form of a narrow, low-divergence beam and with a well-defined wavelength.
A retroreflector is a device that reflects a wave front back along a vector that is parallel to but opposite in direction from the angle of incidence.
Maxwell's equations
Maxwell's equations describe the interrelationship between electric field, magnetic field, electric charge, and electric current as well as the propagation of electromagnetic waves.
Fermat's principle
Fermat's principle or the principle of least time is the idea that the path taken between two points by a ray of light is the path that can be traversed in the least time.
Optical path length
Optical path length is the product of the distance of the path light follows through the system and the index of refraction of the medium through which it propagates.
Lambertian reflectance
A surface exhibits Lambertian reflectance when light falling on it is scattered such that the apparent brightness of the surface to an observer is the same regardless of the observer's angle of view.
James Clerk Maxwell
James Clerk Maxwell (1831 - 1879) was a Scottish mathematician and theoretical physicist whose set of equations in electricity, magnetism and inductance presented a unified model of electromagnetism and light.
Heinrich Hertz
Heinrich Rudolf Hertz (1857 - 1894) was the German physicist who demonstrated the existence of electromagnetic waves by building an apparatus to produce and detect UHF radio waves.
Cyclotron radiation
Cyclotron radiation is electromagnetic radiation emitted by moving charged particles deflected by a magnetic field.
Cauchy's equation
Cauchy's equation is an empirical relationship between the refractive index and wavelength of light for a particular transparent material.
Active laser medium
The active laser medium or gain medium is the material within a laser that exhibits optical gain.
Collimated light
Collimated light is light whose rays are parallel and thus has a planar wavefront
Snell's window
Snell's window is a phenomenon by which an underwater viewer sees everything above the surface through a cone of light of width around 100 degrees.
Optical cavity
An optical cavity or optical resonator is an arrangement of mirrors that forms a standing wave cavity resonator for light waves.
Lasing threshold
The lasing threshold is the lowest excitation level at which the laser's output is dominated by stimulated emission rather than by spontaneous emission.

The Integrated MCAT Course is a trademark of Wisebridge Learning Systems. Unless otherwise specified, the works of the Integrated Course are published under a Creative Commons Attribution NonCommercial ShareAlike License. MCAT is a registered trademark of the Association of American Medical Colleges, which does not endorse the Integrated MCAT Course. The Integrated MCAT Course offers our customers no guarantees regarding eventual performance on the MCAT.