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The solar system
· Greek astronomer Ptolemy- geocentric model- Earth centre of everything
· Polish astronomer Copernicus- heliocentric model- sun centre of solar system
· telescope invented at the end of 16th century
· Greater detail than naked eye
· Italian astronomer Galileo Galilei discovered 4 of Jupiter's moons
· Plotted movement of moons and saw not everything orbited earth.- supported Copernicus' idea
· Church did not approve so Galileo was put under house arrest
· Uranus, Neptune and Pluto discovered through telescope
· Luminous objects give out visible light- waves of energy
· Visible light waves allow people to study distant objects
· Photographs allowed more detailed observations…read more

Slide 3

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Refracting telescopes
· Light travels in straight lines
· Change direction when moving through different materials
· Change in direction= refraction and occurs at interface (boundary) of two materials
· Line at right angle to interface-normal
· Lens transparent block that has been shaped so its interface changes direction of parallel light waves
· A converging or convex lens- curved on both edges, thick in middle
· Light rays converge- together
· In a refracting telescope, a convex (objective lens) creates image
· Eye piece lens- magnifies
· Refraction occurs because light travels at different speeds…read more

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Reflecting telescopes
· Waves are also reflected at boundaries between materials
· This means whenever light passes through a lens some is reflected= fainter image
· This could be a problem if stars are already faint
· Refracting telescopes need to be very long and large magnifications. Large lenses= improve magnification= heavy-
difficult to make perfect shape- images have distorted colours
· In reflecting, those problems aren't present- curved mirror instead of objective lens
· Curved primary mirror focus parallel light rays from distant object into image
· Image magnified by eyepiece lens
· Most modern telescopes are reflecting
· Viewing faint images- telescope needs to collect tiny amounts of light- large diameter of primary mirror- allow maximum
light to enter…read more

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Sea waves- transfer energy-shore-hit cliff-wear away
· Waves in which particles which at right angle to direction of wave is
called transverse waves
· Particles move back and forth in line with direction that the wave is
travelling at
· EM waves- transverse- no need for medium
· Sound waves- longitudinal
· Earthquakes+ explosions- seismic wave- travel through earth.
· longitudinal- push and pull solid rock
· Transverse- move up and down solid rock or side to side
FREQUENCY: number of waves passing a point per second. Hertz- Hz. 1Hz=
I wave per second
WAVELENNGTH: distance from one point of wave to other wave's same
point. Meters- m
AMPLITUDE: maximum distance of a point. Meters, M
Wave speed (m/s)= distance (m)/ time (s)
Wave speed (m/s)= frequency (Hz) x wavelength (m)…read more

Slide 6

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Beyond the visible
Discovery of infrared
· William Herschel- British astronomer.
Dark, coloured filters on telescope to help observe sun safely.
He noticed that different filters heated up telescope to different extent
= different colours = different amount of heat?
To test this he used:
· Prism to split sun light
· Thermometer in one colour and other two on each side of spectrum
· Violet- red hotter
· Infrared found by placing thermometer just after end of spectrum. HOTTEST
Johann Ritter tried to find more `invisible rays'
Used silver chloride- breaks down to give black colour when exposed to light
Turned black fastest just before violet- ultraviolet found
Transfer energy one place to other.…read more

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