P1 Topic 1 - Visible light & Solar System

P1 Topic 1 - Visible light & Solar System

1. The Universe

   • Early model (geocentric)
     • Said that everything orbits the earth
     • Was accepted from the time of the acient greeks to 1500s
   • 1600's (Heliocentric)
     • Said that the earth & everything else orbitted the sun, which is in the centre
       • Galelo's discovery that jupiters moons orbitted jupiter proved the heliocentric model correct

2. Visible light

   • We can see planets that are far away from us because they reflect sunlight. Many discoveries were made using the naked eye, Telescopes have anabled us to discover new things about out universe from things that are further away,

3. Waves

   • WAVELENGTH is the distance from one peak to the nexr
   • FREQUENCY is how many complete waves there are per second 1Hz is 1. 1kHz = 1000Hz & 1MHz = 1000000
   • AMPLITUDE is the height of the wave (from the midline to the peak)
   • SPEED is how fast it goes
   • Waves transfer ENERGY & INFORMATION without transfering MATTER (doesnt move objects)
   • SPEED = FREQUENCY X WAVELENGTH
   • WAVE SPEED = DISTANCE/TIME
   • TRANSVERSE WAVES
     • THE VIBRATIONS ARE AT 90 DEGREES OF THE DIRECTION OF TRAVEL (SIDE TO SIDE)
     • Light & other EM waves, S-waves, Waves on strings & springs, ripples of water
   • LONGITUDINAL WAVES
     • THE WAVES ARE ALONG THE SAME DIRECTION AS THE WAY ITS TRAVELLING
     • Sound & ultrasound, P-Waves, & the push & pull action in slinkys

4. WHEN WORKING OUT THE FORMULA TRIANGLES, THE THING YOUR DIVIDING IS ALWAYS ON THE TOP

5. Relfection

   • When a wave hits a boundary between one medium & another some energy is REFLECTED
   • The angle of INCIDENCE is the SAME as the angle of REFLECTION. The lights reflected due to a change in density

6. Refraction

   • Waves travel at DIFFERENT speeds in DIFFERENT densities
   • When a wave hits a denser material STRAIGHT ON, the waves slows down
   • When a wave hits a denser material AT AN ANGLE, the wave slows down & changes direction - REFRACTING