Physics- paper 1

• The current is the rate at which charge flows through an object.
• Current = Charge / Time
• potential difference (V) is measured in volts, V
• Potential difference is the energy transferred per unit charge between two points in a circuit.
• Power is the rate at which energy is used or produced by a source.
• Resistance is the opposition to the flow of electricity around a component.
• Ohm's law states that the current flowing through a conductor is directly proportional to the voltage across it if its temperature remains constant.
• A series circuit has only one pathway for electrons to travel along.
• In a parallel circuit there are multiple paths for electrons to follow.
• The equation for Ohm's Law is Current = Voltage / Resistance.
• Whats the equation to calculate resistance?


  Resistance = potential difference / current
• What happens to the resistance if a bulb glows brighter?


  It has increased
• What is it called when potential difference is not directly proportional?


  Non ohmic conductor
• How do you measure potential difference?


  Voltmeter (Volts)
• How do you measure current?


  Ammeter- (amps)
• What does the green wire do in a plug?


  Called the earth wire, it is a safety precaution with a potential of 0 incase another wire busts.
• What does the brown wire do in a plug?


  It is the live wire which powers the plug with a potential of 230V
• What does the blue wire do in a plug?


  It is neutral, completing the circuit which has a potential of 0V.
• What will happen if someone touches the live wire when it is loose?


  They will recieve an electric shock.
• Why do you need to switch a circuit off inbetween readings?


  So it doesnt overheat- therefore more accurate results.
• What is the equations for power?

  Current² x resistance OR energy / time
• What does a step down transformer do at a power plant?


  Decreases potential difference for homes, factories etc as they are not able to handle the power otherwise.
• What is irridation?


  Can destroy organisms on food that may cause illness. (Gamma radiation- they will NOT become radioactive)
• What is radioactive contamination?


  Unwanted presence of radioactive particles on materials. -decay and emit radiation
• What is activity of background radiation measured in?


  Becquerels (Bq)
• What is radiation dose measured in?


  Sieverts (Su)
• What are the qualities of gamma radiation?

  Low ionising power high penetrating power
• What are the qualities of beta radiation?

  Medium ionising power medium penetrating power
• What are the qualities of alpha radiation?

  High ionising power low penetrating power
• What type of radiation do we use for treatment and sterilisation?

  Gamma - mostly a long half life
• What is nuclear fission?


  Is the splitting of a large and unstable nucleus into 2 smaller nuclei. This process releases large amounts of energy -can occur in nature
• What radiation is produced when when an unstable nucleus splits?

  Gamma radiation.
• What is nuclear fusion?

  Is the process in which 2 smaller nuclei are fused to form a larger nucleus. Some of this mass is converted into energy.
• What is specific latent heat?

  The energy required per kg to change the state of a substance
• What is inertia?

  The tendency of an object to continue in its current state. If moving, it will want to remain moving. if stationery, it will remain stationary
• What is the fuse in the plug?

  Thin wire that melts if the current gets too high.
• What is specific heat capacity?

  The energy required to change the temperature of 1kg of a substance by 1°C
• What is the charge of an alpha particle?

  Positive
• What is the charge of an alpha particle?

  Positive
• What can be used to stop gamma rays?


  Thick lead or concrete