What are luminous objects?
Luminous objects emit their own light.
What are non-luminous objects?
Non-luminous objects do not emit light, but reflect it.
What is a real image?
A real image is one with rays of light actually passing through it.
What is a virtual image?
A virtual image is one where rays of light do not actually pass through it.
What are four properties of an image created by a plane mirror?
1. The image is virtual
2. The image is as far behind the mirror as the object is in front
3. The image is the same size as the object.
4. The image is laterally inverted
What is refraction?
Refraction is the consequential change of direction after a ray of light has changed speed.
What happens when light slows down?
When light slows down it is refracted towards the normal.
What happens when light speeds up?
When light speeds up is it refracted away from the normal.
What happens when a ray strikes the boundary between two media at 90 degrees?
When a ray hits this boundary at 90 degrees it continues without change of direction.
What is the refractive index?
The refractive index is the ratio between the sine of the angle of incidence and the sine of the angle of reflection.
What symbol is the refractive index represented by?
The refractive index is represented by the symbol 'n'
What is the equation for finding the refractive index?
n=sin i/sin r
What is total internal reflection?
Total internal reflection is where all the light is reflected inside a material.
When does total internal reflection happen?
Total internal reflection happens when the angle of incidence is greater than the critical angle.
What is the critical angle?
The critical angle is the angle of incidence at which the angle of refraction is 90 degrees (perpendicular to the boundary).
What happens when light passes from an optically more dense medium into a less dense one?
When light passes in this way, most of the light is refracted away from the normal, but some light is reflected from the boundary (according to rule of reflection).
What is the equation for finding the critical angle?
sin c=1/n
What symbol is the critical angle represented by?
The critical angle is represented by the symbol 'c'
What is dispersion?
Dispersion is the splitting of visible light into its separate colours when it passes through a prism.
Why does dispersion occur?
Dispersion occurs because each of the different colours of light have a slightly different refractive index, so the colours emerge from the prism, each travelling in a slightly different direction.
Which colour of the spectrum deviates the least?
Red light deviates the least.
Which colour of the spectrum deviates the most?
Violet light deviates the most.