Light Flashcards
What is Light?
Light is a transfer of energy from one store of energy to another.
What and how does light travel in?
Light travels in straight lines. Light rays travels until it strikes a non-transparent object.
What do light rays do?
Light rays show the direction light moves.
Why does the further away the source of light is make it harder to see the light?
Light spreads out so less of it reaches your eye.
Transmitted - transparent material/translucent material
Light hits and passes through
Absorbed - opaque material
Light hits and stops
Reflected or scattered - reflective material
Light hits and bounces off
What is the pupil?
The pupil is a hole that light can go through
What does the back of the eye do?
The back of the eye detects light
What do luminous objects do?
Luminous objects give off light. We can see luminous objects when the light emitted from the enters our eye.
What do non-luminous objects not do?
Non-luminous objects do not give off light.
Law of reflection
Angle of incidence=angle of reflection
Refraction
Refraction is the change in direction of a wave when it changes speed. Typically when it moves from one medium to another. If the waves slows down in the new material it will bend towards the normal. If the wave is faster in the new medium it will bend away from the normal.
What is the critical angle?
The critical angle is when the light ray switches from refracting to reflecting. If the angle to the normal in 42° or above it will reflect if it is lower then it will refract
How do our eyes detect light?
Our eyes only have sensors to detect red, blue and green light. All other colours are perceived as mixtures of these.
What are the three primary colours in light?
Blue, red and green
What do blue and red make?
Magenta
What do blue and green make?
Cyan
What do red and green make?
Yellow
What do blue, red and green make?
White
What happens if you add light to another light?
Any light added to another light makes a brighter light
What colour can light be?
Light can be any colour in the spectrum of colours they differ due to their different wavelengths.
What is white light made up of?
Red,green and blue
What doe white objects reflect?
White objects reflect all the colours of the spectrum
A blue bottle in blue white
Blue light does not contain any other colour, just blue. When it lights up the bottle, the bottle reflects blue light. We see the light that the bottle reflects.
A blue bottle in white light
White light contains all the colours of the spectrum. When the bottle is in white light it reflects blue light. The bottle absorbs red and green light. It absorbs all the colours I white except blue.
What are optical fibres?
OpticaL fibres are used for transmitting light around corners. They are made from very thin flexible glass. Optical fibres carry light signals along their length using total internal reflection. All the light is reflected. This means signals can be sent over long distances. They don’t lose energy for ver6 long.
Optical fibres in hospitals
The doctor is using the optic fibre device to see inside the patients body. Light passes down some of the fibres to light up the inside of the body. Reflected light passes from inside back up other fibres and forms an image of screen.
Optical fibres in industry
Jet engines on aircraft are very complex inside with many small components which all need to be in perfect working order. Technicians can use optical fibres to inspect tiny inaccessible areas.
What is the critical angle?
42°
