Light Flashcards
How does light travel?
In straight lines
What does luminous mean?
An object that emits light
What does emit mean?
Another word for gives out
What does transparent mean?
You can see through the object - because light is not absorbed
What does translucent mean?
Light scatters through the object
What does opaque mean?
You cannot see through the object. The object absorbs or reflects the light.
What is a vacuum?
Empty space. There are no particles.
What is a medium?
A material
How fast is light?
300,000,000 metres per second
What type of wave is light?
Transverse wave
Does light need a medium?
No
How long does it take for light to travel from the Sun to Earth?
8 minutes
Where is light absorbed?
In your eyes
What does transmit mean?
Travels
What does non-luminous mean?
An object that does not emit light
What is a plane mirror?
A mirror with a flat reflective surface
What is the imaginary line at 90 degrees to the surface of a material called?
The normal
What is reflection off a smooth surface called?
Specular reflection
What is reflection off a rough surface called?
Diffuse scattering
State the law of reflection
The angle of incidence is equal the angle of reflection
What is the ray that reflects off a mirror called
The reflected ray
Reflected images are always the wrong way round - this is called? L_______ I________
Laterally Inverted
What is a virtual image?
An image that is not formed on a screen
If an object is 25 cm infront of a mirror, how far away will the virtual images appear behind the mirror?
25 cm
What is refraction?
When light changes direction when it changes medium
When does refraction occur?
When light travels from one transparent medium to another transparent medium (ie water to glass)
Why does refraction occur?
As light changes speed when it goes from one medium to another
What is a lens?
An object that focuses light to a single point
What is a convex lens?
A lens that bring light together to a single point
What is a converging?
A lens that spread light apart
What does the retina do?
It form the image
What does the pupil do?
Transmits light
Is the cornea transparent or opaque?
Transparent
What are the two types of photoreceptors?
Rods and cones
What does inverted mean?
The image is upside down
Where does light enter a pinhole camera?
The pinhole
What happens when light hits the rods and cones?
Chemical reactions produce electrical signals that travels up the optic nerve to your brain
Where is the optic nerve?
At the back of the eye
What does CCD stand for?
charge-coupled device
What is the eye version of the CCD in a camera?
The retina
What is the camera version of the iris in the eye?
The apeture
What are the primary colours?
Red, Blue, Green
What are the secondary colours?
Cyan, Yellow, Magenta
Why are objects a certain colour?
When white light hits an object, it absorbs certain colours and only reflects the colour of the object
What do fliters do to light?
A red filter subtracts all colours from white light apart from red
Why does a green object look black in red light?
As the red light is asborbed by the green object. The green object will only reflect green light.
What can split white light into a spectrum of colours?
A prism
State the colours in order
Red, Orange, Yellow, Green, Blue, Indigo, Violet ROYGBIV
Which colour has the highest frequency?
Violet
Which colour has the lowest frequency?
Red
