Physics

Physics

1. visible light and solar system

   • Ptolemy created the geocentric model which had the earth at the centre and all the other planets orbiting it
   • Coppernicus came up with the heliocentric model in which the sun was at the centre and all the planets orbited it
   • Galileo believed the heliocentric model because after seeing that Jupiter had four moons orbiting the planet it showed that not everything moved around the earth
   • Optical telescopes observe light from above but they cant be used at night or bad weather unlike radio telescopes which are used to detect radio waves from space. Radio telescopes are very large and expensive to make
   • Wave speed= frequancy * wavelength

2. Waves and the Universe

   • Scientists have gotten information that the universe was made froma small point which started expanding and is still expanding today
   • The Steady State Theory suggests that as the universe expands new matter is created all the time

3. Waves and the Earth

   • the normal human range of hearing is between 20 hz to 20 khz
     • sounds above this are called ultrasound and sounds less than this are called infrasound

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