d) Temperature

c) negative temperature coefficient (NTC) thermistor; variation of resistance with temperature

negative temperature coefficient = the property of a material having a lower resistance at higher temperatures

• temperature increases → number density of charge carriers increases

thermistors have a negative temperature coefficient

• graph of resistance against temperature → decreasing gradient

• small change in temperature → larger change in resistance

I-V characteristics

• current → not directly proportional to potential difference

  • non-ohmic conductor

• resistance → decreasing