How Light Travels
Light energy travels in straight lines and the path along which light travels is called a Ray of Light.
The pinhole camera is a device that operates on the principle that light travels on a straight line by producing an object placed in front of it.
The device which can be used to show that light is a form of energy is called a photo electric cell.
Some objects give out light, these objects are said to be Luminous which could be natural self-luminous objects e.g sun, stars, glow-worms, and fireflies, or artificial self-luminous e.g electric lamp, candles.
Also, some objects do not give out their own light, these objects are said to be non-luminous objects e.g moon which produces light as a result of reflection from other sources.
The collection of rays of light is called a Beam of Light which could be convergent, divergent, or parallel. A beam of light is described as parallel when the rays that make it up are parallel.
Divergent is when the rays are moving away from each other as if they had come from a point and convergent when the rays meet or are going to meet at a point.
When light falls on a surface, three things can happen
- The light rays can be reflected
- The light rays can be transmitted
- The light rays can be refracted or absorbed by the material
Rays of light that are sent back from a surface are said to be Reflected. Materials that let light through are said to be Transparent. Those which do not let any light through are said to be Opaque.