The range of wavelengths of radiant energy that are visible to the human eye. Also known as "light". The Illuminating Engineering Society defines the range of visible wavelengths as 380 to 770 nanometers.
Visual acuity commonly refers to the clarity of vision. Visual acuity is dependent on optical and neural factors, i.e., (i) the sharpness of the retinal focus within the eye, (ii) the health and functioning of the retina, and (iii) the sensitivity of the interpretative faculty of the brain.
How something appears to the human eye.
Abbreviated as VA. Also commonly seen as kVA or Kilo-volt-amp. The unit used to measure apparent power. This is the supplied voltage multiplied times the actual current drawn. The volt-amp measurement of a circuit with a power factor of 1.0 is the same as the wattage consumed.
"Drop in voltage levels of the electrical distribution system which interferes with the operation of electrical and electronic equipment. Commonly called 'Brownout'. Results when demand for electricity exceeds capacity of the distribution system." - Advance Ballast Glossary