Light interactions
Learning goals We are learning the properties of light. We are learning how light interacts with objects.
Light travels in a straight line
Light ray A line and arrow representing the direction and straight-line path of light
Light emitted from a source that strikes an object Incident Light Light emitted from a source that strikes an object Incident Light Ray
1. Light can be reflected light “bounces off” the surface of an object and travels in another direction
In A the person sees the object because light travels to their eyes. B shows that light must travel from a source (the lamp) and then reflect off the object toward the eye.
2. Light can be absorbed light energy remains in the object that it hits, and the light energy is converted into heat.
The “E” in the image above appears black because the ink absorbs all of the light that hits it. No light reaches your eyes from the printed “E.”
3. Light can be transmitted light travels through an object and continues travelling. clear glass and plastic transmit most of the light that hits them. light that is not transmitted by an object is either reflected or absorbed.
The coloured windows shown above allow only certain colours to be transmitted. The other colours are reflected or absorbed.
1. Objects can be transparent transmits all or almost all incident light, object can clearly be seen through material Ex. Clear glass
2. Objects can be translucent transmits some incident light but absorbs or reflects the rest, objects are not clearly seen through material
3. Objects can be opaque does not transmit any incident light, objects are not seen through material
Colours and light opaque objects either absorb or reflect light. the colour an object appears to be is determined by the colours of light that are reflected by its surface and the colours that are absorbed by the object.
Under white light, the tomato appears to be red because only the red wavelength is reflected. Under blue light, the tomato appears to be blue.
The apple reflects only red light. The pepper reflects only green light.
Learning goals We are learning the properties of light. We are learning how light interacts with objects.