Electricity - Physics yr8

• What is electricity


  Electricity is the rate of flow of charged particles (electrons)
• What do you need for electricity to flow

  You need a complete circuit for electricity to flow
• Circuit symbols


  Main circuit symbols:

  
• What are circuits


  A circuit is a loop to allow current to flow through, a power source such as a batter supplies he energy for the circuit to actually work
• What is a battery


  Two or more cells put together
• What is a series circuit

  A series circuit is a type of electrical circuit where there is only one loop for current to flow through, the current flows through each component in the same path
• Does the current remain the same in a series circuit

  Yes, the current does not change in a series circuit, the current in each component is equal
• What is a parallel circuit

  A parallel circuit is a type of electrical circuit where there are multiple loops for current to flow through, the components are connected in multiple branches, the current has different paths to flow through each component
• Does the current remain the same in a parallel circuit

  No, the current does not remain the same in a parallel circuit, the total current is divided amongst the different branches
• What is the purpose of circuits

  The purpose of circuits is to allow electricity to flow and to power different electrical supplies, they also transfer energy and can be used to power lights, electronics and others
• What are advantages of series circuits

  -Since the components would be connected in a single path, it would be easier to wire them and you would need fewer materials

  -Since the current throughout the circuit is the same you can easily determine the amount of current flowing through each component
• What are disadvantages of series circuits

  -If one bulb stops working, it interrupts the whole circuit and causes the others to also go off

  -If you add more bulbs, they will go dimmer as it will be harder for electricity to go through more components
• What are advantages of parallel circuits

  -Each component has its own branch for current to flow through, meaning that if a component or bulb fails the other components or bulbs on other branches will still stay on

  -In parallel circuits they allow current to be shared equally between the components which means that all the bulbs will stay bright and work more efficiently

  -It is easier for current to flow through parallel circuits because the current has more paths to go
• What are disadvantages of parallel circuits

  -They are more complex and difficult to wire compared to series circuits

  -They also use more power for each component for its own current in each branch

  -They can also experience voltage drops, which effects the overall performance of the circuit
• What is current


  The rate of flow of electrons per second
• What does it mean if a material has a low resistance 


  It means that it allows electrical current to flow through it easily
• What is resistance


  Resistance acts like a barrier and lowers the ability for current to flow through a circuit
• What does it mean if a material has a high resistance

  It means that it is hard for electrical current to flow through
• What is a conductor 


  A material that allows electrical current to flow through it
• What is an insulator


  A material that does not allow electrical current to flow through it
• What is current measured with


  An ammeter
• What are the units for current

  Amps (A)
• What are the rules for current in a series circuit

  -Current should be the same everywhere in a series circuit

  -Whatever goes into a point on a circuit must come out
• What are the rules for current in a parallel circuit

  -In a parallel circuit the total current entering a circuit should be equal to the sum of the current on each individual branch
• If a switch is open what happens to the current in a circuit

  The current stops moving round a circuit
• If a switch is open what happens to the current in a circuit

  The current has the ability to move round a circuit
• What is voltage


  The energy transferred to or from electrons at a component
• What do you measure voltage with

  A voltmeter
• What units do you measure voltage in

  Volts (V)
• What is resistance measured in


  Ohms
• Where does current flow from on the cells (power source)

  Current always flows from the positive (longer line) to the negative (shorter line)
• Rules for voltage in series circuits

  -Total voltage is equal to the sum of the voltages in each component

  -In series circuits the current is the same between them but the voltage is divided among them
• Rules for voltage in parallel circuits

  -Voltage across each branch is the same

  -In parallel circuits the current entering the circuit is equal to the sum of the current in each individual branch but the voltage is the same across each branch
• How could you make current smaller in a circuit

  You can increase the resistance because resistance can stop the current from flowing
• How is a voltmeter always connected

  A voltmeter is always connected in a parallel with a component
• Why are wires in circuits made from metal

  Metal is a good conductor for electricity and it will allow the current and electrons to flow through the circuit and components easily
• Why are parallel circuits used for house lights

  So they can be switched on and off separately
• When electricity flows through wires what happens to them

  They go hot
• What metal is usually used for wires in electrical circuits

  Copper
• How do you calculate the potential difference (voltage)


  Voltage = current x resistance