Physics Revision 2017

REFLECTION
1. angle of incidence = angle of reflection
2. Regular Reflections
  1. occur at shiny surfaces like mirrors
  2. When a beam of parallel light rays is incident on a smooth and plane surface the reflected rays will also be parallel and it is called the regular reflection
  3. Regular reflection: Reflection from a polished surface is called regular reflection. The rays are parallel. Give glaze to our eyes. Example, plain mirror. Diffused Reflection: Reflection from a rough surface is called diffuse reflection. The rays are not parallel. It makes objects visible. Example, wall.
3. Diffuse Reflections
  1. Rough surfaces like paper
  2. A reflection of light from a surface such that an incident ray is reflected at many angles rather than just one, like a regular reflection!
REFRACTION
1. light travels more slowly in transparent media such as glass, perspex and water than it does in air
2. because the light slows down, a ray of light bends towards the normal when it passes from air into glass, perspex or water
3. air= fast
4. glass= slow
5. diamond= very slow
6. because the light speeds up, a ray of light bends away from the normal when it passes from glass, perspex or water into air
ELECTRICITY
1. Insulators and conductors
  1. Many metals, such as copper, iron and steel, are good electrical conductors. That is why the parts of electrical objects that need to let electricity pass through are always made of metal.
  2. Some common insulator materials are glass, plastic, rubber, and wood. Insulators are used to protect us from the dangerous effects of electricity flowing through conductors.
  3. a complete circuit of conductors is needed for current to flow
2. Circuits
3. Electric charge
  1. can be positive or negative
  2. measured in coulombs (c)
  3. not always measured directly
4. Electric Current
  1. the flow of charge
  2. larger current means more charge per second moving through the circuit
  3. flows from positive to negative
  4. has the same value at all points in a series circuit
  5. depends on the number and voltage of cells and the number and resistance of other components in the circuit
  6. not "used up"
  7. measured in 'coloumbs per second' or amps (A)
    1. measured using an ammeter in series
    2. amps= A
  8. has symbol 'I'
5. Voltage
  1. volts push current around an electric circuit
  2. has symbol 'V'
  3. measured using a voltmeter
  4. measured in joules per coulomb or volts (V)
  5. across a component such as a bulb is the energy changed from electrical to other forms by each coulomb of charge passing through the component
  6. across a cell or power supply is the energy given to each coulomb of charge by the cell or power supply
6. Resistance
  1. opposes the flow of charge
  2. has symbol 'R'
  3. measured in ohms (Ω)
  4. higher resistance means lower current if voltage is kept the same
  5. ‘short circuit’ is a low resistance short cut in a circuit
  6. depends on material
7. Electrical Safety
  1. green and yellow
    1. Earth wire
  2. brown
    1. live wire
  3. blue
    1. neutral wire
Energy resources
1. oil
2. gas
3. coal
4. biomass
5. food
6. wind
7. waves
8. batteries
9. renewable is when something can be used again
  1. solar energy
  2. tidal energy
  3. wind power
10. non renewable is when something is used up
  1. coal
  2. fossil fuels
  3. oil
11. The Sun
  1. (in) directly linked
    1. solar energy
    2. wind energy
    3. hydropower
    4. wave energy
    5. fossil fuels
  2. not linked
    1. nuclear
    2. tidal
      1. moon
    3. geothermal
      1. heat of the earth
12. electricity is generated by means of a variety of energy resources
13. Although energy is always conserved, it may be dissipated (become less concentrated), reducing its availability as a resource.
  1. Principal of Conservation of mass
    1. The law of conservation of energy states that the total energy of an isolated system remains constant—it is said to be conserved over time. Energy can neither be created nor destroyed; rather, it transforms from one form to another.
14. Greenhouse effect
  1. We need to move away from carbon dioxide producing forms of energy resources.
  2. The greenhouse effect is the process by which radiation from a planet's atmosphere warms the planet's surface to a temperature above what it would be without its atmosphere. If a planet's atmosphere contains radiatively active gases (i.e., greenhouse gases) the atmosphere will radiate energy in all directions.
  3. Greenhouse gases such as water vapour, methane and carbon dioxide stop heat escaping from the Earth into space. An increased greenhouse effect can lead to global warming and climate change.
Magnetism and Electromagnetism
1. North-seeking and South-seeking magnetic poles.
  1. like poles repel
  2. unlike poles attract
2. An electric current is surrounded by a magnetic field.
3. A current in a coil produces a magnetic field pattern similar to that of a bar magnet.

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Physics Revision 2017

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	Created by Izzy Pearl (Student-SS) about 7 years ago