Power or capacity to produce a desired effect; → effectiveness.
From L. efficacia "efficacy, efficiency," from efficax "powerful, effectual, efficient," from stem of efficere "accomplish," → effect.
Oskarmandi, → effectiveness.
Fr.: efficacité lumineuse
A measure indicating the ability of a light source to emit visible light using a given amount of → power. It is a ratio of the visible energy emitted to the power that goes into the bulb from the electrical line.