Circuits

• State the rule for current in a parallel circuit

  the total current through the whole circuit is the sum of the currents through the separate components
• What is the unit of charge flow?

  Coulomb ( C )
• Describe the I-V characteristic for a fixed Resistor

  current and potential difference are directly proportional, resistance is constant
• What is a parallel circuit?


  A circuit with more than one route for charge to flow
• State the rule for current in a parallel circuit

  The total current through the whole circuit is the sum of the currents through the separate compartments
• State the rule for potential difference in a series circuit

  The total potential difference of the power supply is shared between the components
• State the equation that links current, potential difference and resistance

  V=IR

  
• What colour is the neutral wire in a three core cable?

  Blue
• What is the reason for the earth wire?

  a safety feature for devices
• What is a series circuit?

  A circuit with only one route for charge to flow
• What is electric current?

  The flow of electric charge
• What is the unit for resistance?


  Ohms

  
• State the rule for current in a series circuit

  The current is the same at every point in the circuit and in every component
• State the equation which links charge flow, current and time

  Q=It

  
• What colour is the live wire in a three core cable?

  Brown
• State the rule for resistance in a parallel circuit

  Adding more resistors in parallel decreases resistance
• What colour is the earth wire?

  Yellow and green
• What is the equation to work out frequency?

  Frequency= 1/time for one wave to pass
• How do you remember where the different wires are placed in a plug?

  bLue goes Left

  bRown goes Right

  earTh goes on Top

  
• What are the ratings fuses normally come in?

  3A 5A 13A 25A
• Why is the earth wire needed on metal appliances and not plastic ones?

  If the live wire becomes loose and touches the casing It makes it live, plastic is not conductive therefore it wouldn’t become live whereas metal coated appliances would become live so it needs the added safety of an earth wire.
• What is frequency and what is it measured in?

  Frequency is how many waves per minutes, measured in Hertz
• What is amplitude when referring to the Oscilloscope?

  the height of waves from midline to peak
• Label the oscilloscope graph

  :)

  
• What is an AC?

  An alternating current, voltage changes from +325V to -325V at a rate of 50 Hertz ( 50 waves passing a point per second )
• What is a DC?

  A direct current, electrons travel out of the negative end of the cell and return to positive end
• What does a diode do in a circuit?

  Stops current flowing round the wrong way
• What is potential difference another name for?

  Volts
• What is resistance a measure of?

  How easy it is for electrons to flow through
• What is current?

  the rate of flow of charge ( how much charge is flowing past per second ) measured in coulombs per second
• What is amps?

  current ( number of electrons )
• What is charge?

  Flow of electrons, coulombs ( C )
• What is potential difference?

  Energy carried, Volts ( V )
• What is resistance measured in?

  Ohms
• Positive charge = loss of electrons
• Negative charge = gain of electrons
• Charge key points:

  . Carried by electrons and protons

  . Measured in coulombs

  . Takes a lot of electrons
• what is amps a measurment for?

  current
• What is current?

  number of electrons
• What is charge measured in?

  coulombs