rp4: I-V characteristics

• 1. use voltmeter to read potential difference across the resistor
  2. use ammeter to read current through the resistor
  3. record these values in a table
  4. adjust variable resistor & record new readings
  5. do this several times to get a range of readings
  6. switch direction of the battery (reverses direction of PD)
  7. take several readings of current & PD
  8. plot a graph of current against potential difference

  
  

  1. repeat but switch resistor with filament lamp
  2. repeat but switch resistor with diode (with an extra resistor)

  
• graph of ohmic conductor ( resistor )

  • current through a resistor is directly proportional to the potential difference
  • we only see this if the temperature is kept constant

  
• graph of filament lamp

  • when the current increases the temperature of the lamp increases which causes resistance to increase

  
• graph of diode

  • in the reverse direction, a diode has a high resistance