P1.1 Flashcards
What is the difference between the geocentric and heliocentric model?
geocentric - sun,moon and planets orbit around the Earth.
most ancient astronomers thought this
Heleocentric - began to replace geocentric in 1600s
sun is at centre of universe
What caused ideas about the solar system to change?
Galileo observed moons orbiting Jupiter
proved the Earth isn’t centre of universe
What is wavelength, amplitude,frequency and speed (0f a wave)?3
What is frequency measured in?
wavelength - distance from one peak to another
amplitude - height of a wave, from midline to peak
frequency - how many complete waves per second, measured in hertz (Hz)
speed - how fast it travels
What is a transverse wave?
Examples?
vibrations at 90 degrees to direction wave is travelling
changes direction
e.g s-waves and all EM waves
What is a longitudinal wave?
Examples?
vibrations along same direction wave travelling
travels in one direction
e.g sounds, shock waves, p-waves
What are the two formulas to work out speed?
speed = frequency X wavelength
wave speed = distance/time
What does a reflected ray look like?
incident ray and releected ray the same, just opposite direction
normal line in centre
What happens when a ray is refracted?
little bit of reflected light
incident ray goes in
wave bends/changes direction as leaves
What is the difference between a real and virtual image?
real image - light from object comes together and forms image on a screen
virtual image - appears to be coming from completely different place
What are converging lenses used for?
to focus light
makes parallel rays of light converge to axis (imaginary line through middle of lens)
What is focal point and length?
focal point - parallel rays meet
lenses have 2, one in front and one behind
focal length - distance from lens to it’s focal point
What lenses does a simple telescope use?
2 converging lenses
one eyepiece and one objective
How does a simple refracting telescope work?
rays from object reach objective lens, already pretty much parallel as coming from so far away
objective lens converges rays to form an image at it’s focal point
rays from image enter eyepiece lens
lens spreads them out so leave at wider angle than entered
light fills more of your retina, image appears magnified
What does a reflecting telescope use?
Hhow
concave mirrors and converging lens
large concave mirror collects parallel rays of light from object
larger mirror reflects light onto smaller second mirror in front of larger’s focal point
smaller reflects light through hole in large collecting mirror
real image formed behind the mirror
converging eyepiece lens magnifies the image
