P2 summary.

  • Created by: Abbs11_
  • Created on: 02-05-16 15:09
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  • PHYSICS 2.
    • Static and current electricity.
      • To stop electrostatic charge building up we can connect the charged object to the ground - this is called earthing.
        • Earthing provides an easy route for the static charges to travel into the ground.
          • This means no charge can build up to give you a shock or make up a spark.
      • Current is the rate of flow of charge around a circuit.
        • In the metal wires of a circuit, this charge is carried by electrons.
          • Charge (Q)  = current (I)  x time (T)
    • Controlling and using electric current.
      • Current - the rate of flow of charge around the circuit.
        • Unit = ampere, A
      • Voltage - the driving force that pushes the current round.
        • Unit = volt, v. can also be called potential difference.
          • Potential difference (V) = current (I) x resistance (R)
      • Resistance - is anything in the circuit which slows down the flow.
        • Unit = ohm
      • If you increase the resistance, then less current will flow.
        • If you increase the voltage then more current will flow.
      • Electrical power (P) = potential difference (V) x current (I)
      • Energy transferred (E)  = current (I) x potential difference (V) x time (T)
      • Light dependant resistor (LDR) changes its resistance depending on how much light there is.
        • In bright light, the resistance falls.
        • In darkness, the resistance is highest.
      • Thermistor (temp dependant resistor.)
        • like an LDR  but its resistance depends on temperature.
          • In hot conditions the resistance drops.
          • In cold conditions, the resistance goes up.
    • Motion and forces.
      • Speed - how fast you're going,
        • Speed  (S) = distance (D) / time (T)
      • Velocity - how fast in a specific direction.
      • Acceleration - is how quickly the velocity is changing.
        • This could be change in speed.
        • Or change in direction.
        • Or both.
        • Acceleration (A) =      change in velocity  (V-u)   / time taken (T)
      • When two forces interact they exert a force on each other.
        • If object A exerts a force on object B then object B exerts the exact opposite force on object A.
      • Resultant force.
        • Force (F) = mass (M) acceleration (A)
        • The bigger the resultant force, the greater the acceleration or deceleration.
        • The bigger  the mass of the object, the smaller the acceleration.
        • To get a big mass to accelerate as fast as a small mass it needs a bigger resultant force.
    • Momentum, energy, work and power.
      • The greater the mass of an object and the greater its velocity the more momentum the object has.
        • Momentum(Kg m/s) = Mass (Kg) x velocity       ( m/s)
      • When a force acts on an object, it causes a change in momentum.
        • Force (N) = change in momentum(Kg m/s) / time (S)
      • When a force moves on an object, energy is transferred and work is done.
        • Work done (E) = Force (F) x distance moved in the direction of the force (D)
      • Power is  something transfers a lot of energy in a short space of time.
        • Power  (P)  = work done (E) / time taken (T)
      • Energy can never be created nor destroyed - only transferred from one form to another.
        • Energy is only useful when its transferred from one form to another.
    • Nuclear fission and nuclear fusion.
      • Ionisation.
        • Atoms can gain or lose electrons. When an atom (with no overall charge) loses or gains an electron it is turned into an ion (which is charged).
      • Nuclear fission.
        • A type of nuclear reaction that is used to release energy from uranium or plutonium atoms.
      • Nuclear Fusion.
        • The opposite to nuclear fission.
        • Two light nuclei collide at high speed and join to create a larger nucleu
          • More energy is created than fission.
        • Only happens at high temperatures and pressure.
    • Using radioactive materials.
      • Background radiation - is low level radiation thats around us all the time.
      • The half life of a radioactive isotope is the time taken for half of the undecayed nuclei to decay.
        • Half-life.
          • A short half life means the activity falls quickly because lots of the nuclei decay quickly.
          • A long half life means the activity falls more slowly because most of the nuclei don't decay for a long time.
      • Uses for: Alpha, Beta, Gamma.
        • Alpha.
          • Used in smoke alarms.
        • Beta.
          • Thickness control in paper mills.
      • Pros and cons of nuclear power.
        • Dangerous.Cant be disposed of safely.
        • Very reliable. Not as risky as perceived.
        • Doesn't release gases such as sulphur dioxide - so clean source of energy
        • Huge amounts of energy created from small amount of nuclear material.
        • Cheap - readily available.
          • However cost of the nuclear power plant is very expensive.









So helpful! I love this!

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