AQA GCSE Physics - Electricity

• Friction

  What is static electricty caused by?
• Negatively charged electrons will be scraped off one and left on another.

  What happens when insulating materials are rubbed together?
• True.


  True or false, do they leave a positive charge on one and s negative charge on the other.
• Electrically charged


  What type of charge does something have to have to attract small objects placed near them?
• Like


  Do like or opposite charges repel?
• Current rule for a series circuit

  Current is the same everywhere
• Current rule for a parallel circuit

  Current in each branch adds up to the current from the battery
• Potential difference rule for a series circuit

  pd across each component adds up to the total pd across all components
• Potential difference rule for a parallel circuit

  Voltage across each branch is the same as the voltage from the battery
• Resistors in series


  Total resistance equals the sum of the resistorsRT = R1 + R2 ...
• Resistors in parallel


  1/RT=1/R1+1/R2...
• Electrical power equation

  P = IV(I = current/A)
• Resistance equation


  R = V/I(I = current/A)
• Electrical charge equation

  Q = ItQ, Charge in Coulombs (C)I, current in Amps (A)t, time in secs (s)
• Potential difference equation

  V = E/QV, pd in Volts (V)E, Energy in Joules (J)Q, Charge in Coulombs (C)
• Potential difference

  Work done per unit chargeOR Electrical energy given to an electrical component per Coulomb
• Why resistance of a wire goes up as it gets hotter

  •Free electrons hit the positive metal ions•The ion lattice vibrates faster•Harder for electrons to get past
• I-V graph of a wire(Constant physical conditions)

  
• I-V graph of a lamp

  
• I-V graph of a diode

  
• I-V graph of a thermister

  
• Current at a junction

  All of the currents into a junction add up to the total of the currents out of the junction
• Voltmeter symbol

  
• Variable Resistor

  
• power supply ( several cells)

  
• Conducting Wire

  
• resistance (R=V/I)


  A measure of how hard it is for current to flowMeasured in Ohms (Ω)
• resistor graph

  
• filament graph

  
• diode graph

  
• series circuit


  -current is the same everywhere-emf/voltage is sharedRn=R1+R2+...+Rn

  
• parallel circuit


  -current is split-emf/voltage is the same everywhere-1/Rn=1/R1+1/R2+...+1/Rn

  
• Electron


  a subatomic particle that has a negative charge
• Conductor


  A material through which charges can easily flow
• Insulator


  a material through which charges cannot easily flow
• Circuit


  an electrical device that provides a path for electrical current to flow
• Series circuit


  circuit that has only one path for electric current to follow
• Parallel circuit


  a closed circuit in which the current divides into two or more paths before recombining to complete the circuit
• Charge (Q)

  Fundamental property of matter that produces all electrical effects
• Coulomb (C)


  the unit for electrical charge.