I-V Characteristics and Circuit Devices

• What is the I-V characteristic of an ohmic conductor at constant temperature?

  Current is directly proportional to potential difference
• Why does the resistance of an ohmic conductor not change?

  Because current is directly proportional to potential difference
• What type of graph represents the I-V characteristics of an ohmic conductor?

  The graph is linear
• What happens to the resistance of a filament lamp as current increases?

  Resistance increases
• Why does the resistance of a filament lamp increase with current?

  Because the temperature of the filament increases
• How does the I-V characteristic graph of a diode differ from that of an ohmic conductor?

  Diode graphs are non-linear
• What is the behavior of current in a diode?

  Current only flows in one direction
• What is the resistance of a diode in one direction?

  High resistance
• What factors affect the resistance of an LDR and a thermistor?

  • LDR: Resistance depends on light intensity
  • Thermistor: Resistance depends on temperature
• In what condition does an LDR have lower resistance?

  In brighter light
• In what condition does a thermistor have lower resistance?

  In hotter temperatures
• What are common uses for LDRs and thermistors?

  • LDR: Automatic night lights
  • Thermistor: Thermostats
• What are the characteristics of series circuits?

  • Current is the same through all components
  • Total resistance is the sum of individual resistances
• What are the characteristics of parallel circuits?

  • Total current is the sum of currents through each branch
  • Total resistance is less than the smallest individual resistance