resistance - rpa 3

• R=V / I

  to find resistance
• equipment:

  • ammeter
  • voltmeter
  • meter ruler
  • crocodile clips
  • wire
  • battery
• 1. attach wire onto a meter ruler with tape
  2. use crocodile clips on selected length to attach the wire to the ciruit
• in this RPA we are investigating how the length of the wire increases the resistance
• resistance is directly proportional to the length of the wire
• zero error:

  • zero error is the reading on a measuring equipment when the value should be zero
  • this is a systematic error
  • it cannot be reduced by repeating
  • for all your reading you need to subtract the zero error
• what causes zero error due to equipment:

  • the crocodile clips cant get on the exact zero position of the ruler
  • resistance from the clip and wire
• issue - heating affect

  • an increased temperature will increase the resistance therefore increasing heat
  • to reduce this we should turn the switch off when were not taking a reading
  • we can also use a low potential difference to keep the current low reducing heating
• a variable resistor can be used to change the length of the wire as its a long piece of coiled wire