Visual performance
Degree of effectiveness of the visual system, measured for example by the speed and
accuracy with which a visual task is accomplished.
Visual task
Set of elements of the work performed.
Voltage drop
Voltage drop (Vf) is a synonym of the potential difference. More specifically if a resis-
tor of resistance R is inserted between two points A and B of an electrical circuit and
traversed by a current of intensity I, Ohm’s law states that the electric potential at A is
greater than at B in a quantity equal to R·i. In other words, between A and B there is
a potential difference, or voltage drop, equal to ΔV = R·I
W
Wall washer
Luminaire designed to illuminate the walls of buildings, whether external or internal;
wall washers can be with white light or RGB, they are very frequently used to create
spectacular effects outside.
Warm white
White colour of a light source with a colour temperature between 2700 and 3500
Kelvin.
Wavelength
Distance between two successive points, in the direction of propagation of a periodic
wave, in which the oscillation has the same phase. Measured in metres (m) and nano
metres (nm).
Wide Flood
Term to identify a 2 ½ theta opening between 20 and 30° in a projector.
