Is the persistence of sound after the cause of sound has stopped-a result of repeated reflections.

Is perceived as a buzzing or clicking sound, and it is comprised of repeated echoes traversing back and forth between two non-absorbing parallel surfaces.

In physical principles of light, it is the light rays

leaving the source strike through, opaque surface

which spreads the light in various directions, in

addition light is broken up while in reflection, the

light bounces back at a different direction.

The number of times the cycle of compression and rarefaction of air makes in a given unit of time.

In theory and fundamentals of lighting. It is the

science that deals with measurement of light.

It is the unit of luminous flux, amount f light falling

on a surface from the source.

Lighting used primarily to draw attention to particular

points of interest.

A louvered construction divided into cell-like areas and

used for redirecting the light emitted by an overhead source.

A type of perimeter detector which is subject to false

alarm from aircraft radar and from movement outside building through window, wood doors, and the like. It uses radio waves.