Physics colour and lenses Flashcards
Put these in order from longest to shortest wavelength.
Green, Blue, Yellow, Red, Violet
Red as the longest wavelength, violet the shortest.
- red
- orange
- yellow
- green
- blue
- purple
- violet
Put these in order from longest to shortest wavelength.
Radio, X-rays, Infrared, UV, Visible light
- radio
- microwave
- infrared
- visible
- ultraviolet
- X-ray
- gamma ray
What is white light made up of?
- all of the colours of the spectrum
What are the primary colours?
Red, Green, Blue
What are the secondary colours?
Yellow, Magenta, Cyan
What does mixing two primary colours make?
- a secondary colour
What does mixing all the primary colours make?
- white
What colour would you get if you mixed green light and blue light?
When green and blue combine you get cyan light.
White light shines on a red filter.
What colour(s) does the filter block?
A red filter blocks all colours of light except red.
So a red filter only allows through red light.
If magenta light shines through a red filter, what colour light appears behind?
Magenta is made up of red and blue light.
The red filter absorbs the blue light, so once again only red light reaches the other side.
If cyan light shines through a red filter, what colour light appears behind?
Cyan is made up of green and blue light.
The red filter absorbs the blue and green light, so no light reaches the other side.
What is white light made up of?
White light is made up of the spectrum of colours.
What do primary colours do?
Primary colours combine to get secondary colours.
What do the filters absorb?
Filters absorb colours other than the filter. A blue filter would only allow blue light through.
Can opaque objects be seen through?
Opaque objects cannot be seen through and their colour depends on pigments in the surface materials.
If I have a white object and shine red light onto it, what colour would it appear?
The object would appear red, since white light contains all the colours of the spectrum, but the red object only reflects red light
If I shine yellow light onto a cyan object, what colour would it appear?
Yellow light is made up of red and green.
A cyan object can only reflect blue or green.
The red is absorbed.
There is no blue light to start with.
So the only colour reflected is green
If I shine magenta light on a green object, what colour will it appear?
Magenta light is made up of red and blue.
A green object can only reflect green.
The red and blue are absorbed.
There is no green light to start with.
So no colour is reflected, the object appears black.
What does the colour of an object depend on?
Objects appear different colours based on what they reflect.
A red object will reflect red light but absorb other colours.
What do transparent objects allow?
Transparent objects allow all the incident light to pass through, none is absorbed.
What do translucent objects allow?
Translucent objects let light pass through but it is scattered or refracted. A frosted window would be translucent.
What passes through an opaque object?
No light passes through an opaque object.
What happens when light passes into a lens?
The light slows down as it enters the lens
What does the word converge mean?
Converge means the lines will meet at a point.
This means parallel rays of light will converge to a point when they pass through a convex lens.
