Illuminance defines the amount of light reaching a certain place, also know as the luminance intensity.
Example: As I am far from the candle, the illuminance is very low.
pt_br: Iluminância.
Light
Noun.
Light is a form of electromagnetic radiation with a wavelength which can be detected by the human eye.
Example: The light from the TV hurts my eyes.
pt_br: Luz.
Opaque.
Adjective.
A object that light can't pass through.
Example: My hand is opaque, light can't pass through it.
pt_br: Opaco.
Penumbra.
Noun.
The partially shaded outer region of the shadow cast by an opaque object.
Example: In a solar eclipse, the part that is partially dark is the penumbra.
pt_br: Penumbra.
Reflection.
Noun.
When light hits and object and it returns, the object don't absorb light and light continued its path.
Example: The mirror works using reflection.
pt_br: Reflexão.
Refraction.
Noun.
It is when light is traveling at a substance and it enters an area that has a different substance, this change in the environment makes the light change its direction.
Example: A prism refracts light.
pt_br: Refração.
Shadow.
Noun.
A black area in a surfaced caused by the block of the light source.
Example: I saw my mom coming from my back by her shadow.
pt_br: Sombra.
Translucent.
Adjective.
Any object that allows light to pass, but not totally.
Example: When we put a piece of paper exposed to the light, a part of the light passes, then it is translucent.
pt_br: Translúcido.
Transparent.
Adjective.
An object that light can fully pass through.
Example: We cleaned the glass, and now it is transparent.
pt_br: Transparente
Umbra.
Noun.
The umbra is the innermost and darkest part of a shadow.
Example: The umbra can be seen in a solar eclipse, the middle part is darker (umbra) than the part closer to the border.
