# Core Physics - Topic 1 Visible Light & The Solar System

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• Created by: Katie
• Created on: 09-04-13 17:34

## The Solar System

Copernicus - HELIOCENTRIC                  Ptolemy - GEOCENTRIC

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## The Solar System Continued

• PtolemyGEOCENTRIC
• Sun, Moon and planets move in orbits
• Everything obits the Earth
• Copernicus - HELIOCENTRIC
• Moons orbit the planets
• Planets obit the Sun
• Telescopes improved - Planets discovered
• Uranus, Neptune and Pluto
• Luminous objects in space give out visible light
• Travels as waves of energy
• Visible light waves allow studying of distant objects
• Objects in space give out other types of waves
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## Refracting Telescopes

• Light travels in straight lines but can change direction
• Change in direction - REFRACTION
• Occurs at the interface between 2 materials
• A lens is shaped so its interface changes directions of parallel light waves
• A converging/convex lens
• curved on both sides making a thicker middle
• light rays enter and come together - converge
• focuses the rays
• Distance between focus and lens = focal length
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## Waves

Traverse waves - particles move at right angles to the direction wave is travelling
Longitudinal waves - particles move back and forth in the direction wave is travelling

• Electromagnetic waves
• Traverse
• Do not need a medium to travel through
• Seismic waves
• Earthquakes, explosions
• Longitudinal or traverse
• Travel through the Earth
• Sound waves
• Longitudinal
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## Waves Continued

• Wave frequency
• Number of waves passing a point each second
• Measured in hertz (Hz)
• 1 Hz = 1 wave per second
• Wavelength
• Distance from a point on one wave to the same point on the next
• Measured in meters
• Amplitude
• Maxium distance of a point on the wave from its rest position
• Measured in meters
• Wave speed
• How fast the energy in a wave travels

Wave speed (m/s) = distance(m)                v = x
time(s)                        t

Wave speed (m/s) = frequency (Hz) x wavelength (m)        v = ⨍ x λ

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