P

• electrical current flows from the negative end of the cell to the positive end 
• electrons are carrying energy from the cell which they pass energy to all the components in a circuit 
• Conventional current is when scientists thought current flowed from positive end of the cell to the negative end of the cell 
• • electric current is displayed as conventional current 
• series circuits is a circuit with no branches in which current can only flow in one direction 
• an electrical current is a flow of charge around a circuit 

  the unit is called ampere/(A)
• current in the circuit is measured using ammeter in series with a component
• current is never used up in a circuit, in a series circuit current is the same all the way around
• a parallel circuit is a circuit with multiple branches
• in a parallel circuit the current splits and some current passes through both of the branches 
• in parallel circuits the current in the branches adds up to the total current leaving the cell 
• energy transfers involved in a cell: 

  the cell has a store of chemical energy which is transferred to electrical energy and that’s carried by electrons passing out of the cell when the cells pass through the components the electrical energy is transferred to other formed of energy 
• potential difference (voltage)
• potential difference of 1 volt tells us that 1 joule of energy is transferred for each coulomb of charge that is moving through the circuit 
• potential difference is measured with an voltmeter in parallel to a component
• potential  difference in series circuit is shared between components total potential difference across lamps is the same as the potential different across the cell
• If two resistors are connected in parallel, what can be said about their combined total resistance?

  Their total resistance is less than the smallest of the two individual resistances.
• battery is 2 or more cells connected together 

  • cells in batteries must be connected in the same direction 
• as the number of batteries increases the potential differences across a circuit doubles 
• electrical charge is measured in coulombs (C)
• a current of one ampere means we have 1 coulomb of charge flowing per second 
• size of the electrical current is the rate of flow of electrical charge
• resistance tells us the amount of potential difference required to drive a  current through a component 
• current through a resistor is directly proportional to the potential difference. resistance is constant does not change if we increase the current this resistor is called an ohmic conductor, 

  • resistance will only stay constant the temperature is constant 
• in a filament tamp the current is not directly proportional to the potential difference as the filament gets hot which causes the resistance to increase, as high temperatures the atoms in a cell vibrate more that means electrons in the current collide more atoms so more energy is needed to push current through 
• the current through a diode flows in only one direction this is because the diode has a very high resistance in the reverse direction 
• current/potential difference graph for a diode

  
• LED

  • only allows current to flow in one direction 
  • gives off light when current flows through 
• resistors in series add together as current has to pass each resistor in turn
• The total resistance of two resistors in parallel is less than the resistance of the smallest individual resistor 
• blender and fan transfer electrical energy into kinetic energy of electric motors 
• iron and a kettle transfer electrical energy into thermal energy 
• in a hair dryer and washing machine electrical energy is transferred to kinetic energy of electrical motors and thermal energy 
• power is the rate at which energy is transferred 

  • 1 watt (W) is an energy transfer of 1 J per second 
• the current in a cell is a direct current (DC) as it only moves in one direction   

  the mains electricity in the uk is alternating current 
• • in AC the current is constantly changing direction 
• the benefit of AC is that it is very easy to use a transformer to increase or decrease the potential difference 
• in the UK alternating current has a frequency of 50 hertz (Hz) 

  in the UK altering current has a potential difference around 230 volts 
• scientist can see the pattern of an electrical current using a machine called oscilloscope 
• the coating of a 3 core cable is made of plastic which does not conduct electricity