| A | B |
|---|
| light | the electromagnetic waves that make things visible and can be perceived by the eyes |
| ray | a narrow beam of light |
| ray diagram | a line diagram which shows the direction in which light waves are traveling |
| luminous | object that gives off or emits its own light |
| non-luminous | something that does not give off or emit light |
| transparent | allows light to pass through it |
| translucent | allows some light to pass through it |
| opaque | does not allow light to pass through it |
| shadow | a region where light has been blocked off from a source by an opaque object |
| *intensity | a measure of the brightness of a light source; measured in units of candela |
| *electromagnetic spectrum | the complete range of electromagnetic radiation from the longest radio waves to the shortest gamma radiation |
