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AST101H1 (500)
Lecture

October 11


Department
Astronomy & Astrophysics
Course Code
AST101H1
Professor
Michael Reid

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what is light?
Alhazen (Persian): particles, travels in straight line, made pin hole camera. realized hoe
the eye works
Newton: described lights as particles and how it works. bounces off
Descartes: more sense if they’re waves built telescope with lenses
Huygens: a prism can’t be explained as particles
particles:
travels in straight lines yes
reflection yes
different colors/prism ish
refraction ish
interference ish
photo-electric effect yes
waves:
travels in straight lines ish
reflection ish
different colors/prism yes
refraction yes
interference yes
photo-electric effect no
newton built telescope with mirrors
waves: cancel or strengthen each other
hertz: discovered electro magnetic waves
both particles and waves
and so are protons, neutron, and everything else
all lights travels at the same speed, 300,000 km per second (i.e. the speed of light)
ultraviolet - visible light - infrared
electromagnetic spectrum: includes all waves
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