Module 5
1. Module 5
1.35. Module Glossary
Module 5—Wave Theory of Light
Module Glossary
antinode: the opposite of node, a point on a standing wave pattern where there is maximum displacement
bright fringes: regions of constructive interference along antinodal lines
constructive interference: occurs when two waves combine to produce a resultant wave larger than either of the original waves
converging lens: a lens that refracts rays travelling parallel to the principal axis inward to the focal point of the lens
critical angle: for any two mediiums, the size of the incident angle that causes the angle of refraction to be 90°
dark fringes: regions of destructive interference along nodal lines
destructive interference: occurs when two waves combine to produce a resultant wave smaller than either of the original waves
diffraction: the bending and spreading of waves when they interact with obstacles in their path
diffraction grating: an optical component that has a surface covered by a regular pattern of parallel lines or grooves that are usually separated by a distance comparable to the wavelength of light
diverging lens: a lens that refracts rays travelling parallel to the principal axis outward so that they appear to have originated or passed through the virtual focal point of the lens
electromagnetic spectrum: a general classification of all electromagnetic radiation based on wavelength, frequency, and energy
frequency: the number of cycles per unit of time (Hz = 1 cycle/second)
incident ray: an incoming ray of light
node: a point on a standing wave pattern where there is no displacement and it appears to be standing still
normal line: a straight, dashed line drawn perpendicular to the mirror surface at the point of reflection
Θi (Θin): the angle between the incident ray and the normal line
Θr (Θout): the angle between the reflected ray and the normal line
polarization: the production of a state in which the plane of the electric field for each electromagnetic wave occurs only in one direction
reflected ray: an outgoing ray of light
refraction: a change in the direction of a wave due to a change in its speed
refractive index: a ratio comparing the speed of light in a vacuum to its speed in a given medium
Snell’s Law: for any angle of incidence greater than zero, the ratio of 
thin lens equation: an equation that relates image distance, object distance, and the focal length of a thin lens
total internal reflection: the reflection of a wave that is travelling from a high-index medium into a low-index medium at an angle equal to or greater than the critical angle
wavelength: the distance between adjacent points on a wave that vibrate in phase with one another (m)