Visible light and the solar system Flashcards
What is the geocentric model
The sun moon planets and stars all orbited the earth
In perfect circles
It was created by the Ancient Greeks in the 1500s
What is the heliocentric model
The earth and the planets all orbit the sun which is at the centre of the universe
It was introduced by Copernicus in 1543
The orbits are in elliptical shape not circles
What were Galileos observations and what did they prove
In 1610 he was observing Jupiter using a telescope when he saw three stars in a line near the planet
When he looked again the next evening he saw the stars had moved in the wrong direction in the night sky
He soon realised that these objects weren’t stars but moons orbiting Jupiter
They showed not everything orbited the Earth which proved the geocentric model wrong
How did early astronomers observe the universe
Using the naked eye
They could only see the objects that were hit and gave out lots of visible light
Naked eye observations are only really useful for mapping positions
How do telescopes help us observe the atmosphere
They magnify images so more distant objects can be seen in more detail
We can see objects that are further away
And discover more about what the universe is made up of
How do photographs help us observe the atmosphere
They can be taken using telescopes so you can zoom in and look closer
We can monitor objects by taking pictures of them at different times and compare them to share with others you can see faint objects by having a long exposure time
What is wave length
The distance form the peak of one wave to the next
What is frequency
How many complete waves pass a point per second
It is measured in hertz
1hz is one wave per second
What is amplitude
The height of the wave from the mid line to the top of the wave
What is speed of a wave
How fast the wave goes
What do waves do
They transfer energy and information without transferring energy
Speed of wave=
Frequency x wavelength
What is a transverse wave
The vibrations are at 90 degrees to the direction of travel of the wave Light and other em waves S waves Waves on strings or springs Ripples on water
What is longitudinal wave
The vibrations are in the same direction as the wave is travelling
Sound and ultrasound
P waves
Slinky spring when you push and pull the end
What is reflections
When a wave hits a boundary between one medium and another some energy is reflected
The angle of incidence is the same as the angle of reflection
What is refraction
When a wave crosses a boundary between two mediums it changes speed
When the boundary is denser it slows down
When the boundary is lighter it speeds up
What is a real image
When light from an object comes together to form an image in a screen
What is a virtual Image
When the light appears to be coming from a different place
This happens in a mirror and in a magnifying glass
What Happens with a converging lens
They’re convex so cause parallel rays to move together
The axis passes through the middle of the lens
The focal point is where all of the rays meet
Each lens has a focal point before and after the lens
How to draw a ray diagram for a converging lens
Draw a point from the top of the object to the lens parallel to the axis
Draw another ray from the top of the object through the axis
The first incident ray is refracted through the focal point
The point where the two rays meet is the top of the Image
How can you find out the distance from the lens to the focal point
Clamp a lens at one end of the track
Clamp a piece of white card further down
Set it up near a window with the lens directed at a distant object
Move the card along the track until the image is focused then clamp when you have the best Image
Use a ruler to measure the distance between the card and lens
How does a refracting telescope work
It has an eyepiece and an objective lens
The objective lens converges the rays
The rays of light from the objective go to the eyepiece and the lens spreads them out so the image is magnified and becomes virtual
How does a concave mirror work
An incident ray parallel to the the axis will pass through the focal point when reflected
An incident ray passing through the focal point will be parallel to the axis when reflected
How to draw a ray diagram for a concave mirror
Draw a ray from the top of the object to the mirror parallel to the axis
Draw another line from the top through the focal point to the mirror
The parallel incident ray is reflected brought the focal point
The other incident ray is reflected parallel to the axis
Where the two rays meet is the top of the Image
