Unit 1 Universal Physics Topic 1 Visible Light in addition to the Solar System Our underst in addition to ing of the universe Evidence as long as the Heliocentric Model Observing the Universe
Lusk, Brianna, Features Reporter has reference to this Academic Journal, PHwiki organized this Journal Unit 1 Universal Physics N Smith St. Aidans (EdExcel) Topic 1 Visible Light in addition to the Solar System Our underst in addition to ing of the universe Up until the 16th Century people believed that the Earth was the centre of the universe this is called the Geocentric model in addition to I made a model of the universe based on it. I published my On the revolutions of the celestial spheres just be as long as e my death in addition to showed that the Earth in addition to other planets orbit around the sun the Heliocentric model.
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Evidence as long as the Heliocentric Model I helped develop the modern telescope in addition to made measurements with it that proved that the Copernican model of the solar system was correct. Observing the Universe What are the advantages in addition to disadvantages of each of these methods An introduction to Waves A Wave is a movement of energy but NOT a transfer of matter
Wave definitions 1) Amplitude this is how high the wave is: 2) Wavelength () this is the distance between two corresponding points on the wave in addition to is measured in metres: 3) Frequency this is how many waves pass by every second in addition to is measured in Hertz (Hz) 4) Speed this is how fast the wave travels in addition to is measured in metres per second (m/s) Transverse vs. longitudinal waves Transverse waves are when the displacement is at right angles to the direction of the wave. Longitudinal waves are when the displacement is parallel to the direction of the wave Examples light, other EM waves, some seismic waves Examples sound, some seismic waves Refraction through a glass block: Wave slows down but is not bent, due to entering along the normal
Refraction Refraction is when waves – – or slow down due to travelling in a different –. A medium is something that waves will travel through. When a pen is placed in water it looks like this: In this case the light rays are slowed down by the water in addition to are –, causing the pen to look odd. The two mediums in this example are — in addition to -. Words speed up, water, air, bent, medium Lenses Lenses use the idea of refraction:
Another example: The lens in the eye is used to focus what we see: Converging in addition to diverging lenses CONVERGING (Convex) Thickest at the centre DIVERGING (Concave) Thinnest at the centre Ray diagrams as long as lenses 1 The rays of light are refracted INWARDS in addition to meet at the focus, F. The image as long as med is REAL in other words, it can be seen on a screen The rays of light are refracted OUTWARDS. A VIRTUAL image is as long as med in other words, the image doesnt actually exist F F A distant object
Lenses in Telescopes Because stars are very far away, the rays of light from them enter a telescope effectively parallel: The objective lens basically gathers as much light as possible from the distant star in addition to focuses it inside the telescope. The eyepiece lens then magnifies this image into the eye. Mirrors in Telescopes Astronomical telescopes tend to use large concave mirrors as well as a convex lens. This allows them to collect more light: The Wave Equation All E-M waves obey the Wave Equation: Wave speed (v) = frequency (f) x wavelength () in m/s in Hz in m
A water wave has a frequency of 2Hz in addition to a wavelength of 0.3m. How fast is it moving A water wave travels through a pond with a speed of 1m/s in addition to a frequency of 5Hz. What is the wavelength of the waves The speed of sound is 330m/s (in air). When Dave hears this sound his ear vibrates 660 times a second. What was the wavelength of the sound Purple light has a wavelength of around 6×10-7m in addition to a frequency of 5x1014Hz. What is the speed of purple light Some example wave equation questions 0.2m 0.5m 0.6m/s 3x108m/s Distance, Speed in addition to Time as long as waves A water wave travels 200 metres in 40 seconds. What is its speed Another wave covers 2km in 1,000 seconds. What is its speed Sound travels at around 330m/s. How long does it take to travel one mile (roughly 1,600m) Light travels at a speed of 300,000,000m/s. How long would it take to travel around the world if the diameter at the equator is around 40,000km Topic 2 The Electromagnetic Specturm
The Visible Spectrum In the 17th Century I did lots of work on light in addition to wrote about how visible light was made of the colours of the spectrum. I accidentally discovered that, if you put a thermometer here, it gets hot. I discovered Infra Red radiation!! I then discovered ultra violet by observing how salts made from silver were lightened by something just beyond violet light. Electromagnetic Radiation E-M radiation is basically a movement of energy in the as long as m of a wave. Some examples: The Electromagnetic Spectrum Each type of radiation shown in the electromagnetic spectrum has a different wavelength in addition to a different frequency: Each of these waves travels at the same speed through a – (300,000,000m/s), in addition to different wavelengths are absorbed by different surfaces (e.g. infra red is absorbed very well by — surfaces). They all travel as — waves. The more dangerous waves are at the high – end of the spectrum. Words black, transverse, long, short, vacuum, frequency
The Electromagnetic Spectrum Type of radiation Uses Dangers Gamma rays X rays Ultra violet Visible light Infra red Microwaves TV/radio Treating cancer, sterilisation Medical, airport scanners Sun beds, security Seeing things, photos Remote controls, heat transfer, optical fibres Satellites, phones Communications Cell mutation Cell mutation Skin cancer None (unless you look at the sun) Skin burns Heating of cells Very few Introduction to Radioactivity Some substances are classed as radioactive this means that they are unstable in addition to continuously give out radiation: Radiation The nucleus is more stable after emitting some radiation this is called radioactive decay. Radiation like this can be either alpha, beta or gamma radiation. Ionisation Radiation is dangerous because it ionises atoms in other words, it turns them into ions by knocking off electrons: Ionising radiation is emitted by radioactive sources all the time. Ionisation transfers energy to cells in living tissue, causing them to mutate, usually causing cancer.
Topic 3 Waves in addition to the Universe Space: An introduction OUR SUN is one of millions of stars that orbit the centre of THE MILKY WAY, which is one of a billion galaxies that orbit AND move away from the centre of THE UNIVERSE, made up of everything!! How our Earth in addition to the Sun compare to others
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