P1- TOPIC 1
- Created by: SanaaM
- Created on: 22-02-16 16:27
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- P1.1 Visible Light & Solar System
- 1.Modelling the Solar System
- Two models were designed to represent our Solar System
- Geocentric by Ptolemy - Earth was stationary and was orbited in circular orbits.
- Heliocetric by Copernicus-Planets orbitted the Sun in circles. Planets further from the Sun moved slowly. Moon went around the Earth
- Galileo's discovery of Jupiter's 4 moons proved the Geocentric model wrong (which was previously believed correct by the church)
- Two models were designed to represent our Solar System
- 2. Observing the Universe
- Introduction of telescope (17 century)
- Telsecope gather more light = brighter and larger images.
- Telescopes became bigger = easily see fainter/ distant objects
- Arrival of Photography helps keep permanent record of observations
- Solar System .. Sun, 8 planets, asteroid belt between mars and Jupiter (largest (Ceres), Kuiper belt and Proxima Century (Nearest Star)
- Introduction of telescope (17 century)
- 3. Reflection and Refraction
- Laws of Reflection= angle of i and angle of r are equal.
- All waves can be reflects - sound waves off buildings/walls and Dolphins/bats reflect Ultrasound to monitor their surroundings.
- Refraction is the change in direction (due to change in speed) when light enters a different medium.
- When entering a denser medium it bends towards normal
- When entering less dense medium it bends away from normal
- 4. Lenses
- Converging Lens - Thickest in middle, brings rays to a point
- Diverging Lens- thinnest in middle, scatters ray
- Focal Point= where rays meet Focal legnth= distance between centre of lens and focal point
- Real Image= inverted and when object is at a distance
- Virtual Image is when object is between lens and focal point so image is not formed on screen
- 5. Telescopes
- Refracting Telescopes - objective and eyepiece lens are both converging.
- Converging lens focuses image of a distant object at focal point
- Eyepiece magnifies the image
- Reflecting Telescopes- made of concave mirror, a flat mirror and an eyepiece
- Concave mirror forms image at focal point
- Flat Mirror reflect rays toward eyepiece
- Eyepiece magnifies the image
- Refracting Telescopes - objective and eyepiece lens are both converging.
- 6.UnderstandWaves
- All waves transfer energy and not matter, create vibrations
- Upper part of wave = peak and lower part of wave = trough
- Wavelength is distance between peak/trough
- Amplitude is maximum displacement of wave
- Frequency of waves measure in Hz (complete vibration/sec)
- 7.Two Types of Waves
- Transverse Waves
- EM Waves (light)
- Vibrate at right angles to the direction the waves are going in.
- S Waves (seismic)
- Do not need a medium to travel (can travel through space)
- Longitudinal Waves
- Particles vibrate back and forth in parallel to the direction the wave is going
- Need a medium to travel through (sound cannot travel through space)
- P- Waves (Seismic)
- Transverse Waves
- 1.Modelling the Solar System
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