1. ammeter voltmeter cell Indicator / light source diode Light emitting diode resistor Variable resistor thermistor Light dependent resistor heater Electric motor 4.4 Components and their characteristics

2. ammeter voltmeter cell Indicator / light source diode Light emitting diode resistor Variable resistor thermistor Light dependent resistor heater Electric motor 4.4 Components and their characteristics

3. Many cells = a battery No more semi circles! of a specific value Resistance falls as temp rises Low resistance, connect in series High resistance, connect in parallel Emits light when forward biased Resistance falls as light level rises Conducts when forward biased

5. Changes current Changes pd Main advantage is that the pd and current can be reduced to zero 4.4 Components and their characteristics

6. Changes current Changes pd Main advantage is that the pd and current can be reduced to zero 4.4 Components and their characteristics

7. V I + - - + wire V I + - - + lamp V I + - - + High temp low temp V I + - - + 0.6 V thermistordiode Amps Milli-amps

8. V I + - - + wire V I + - - + lamp V I + - - + V I + - - + 0.6 V thermistordiode

9. 4.4 Components and their characteristics Resistance and temperature For metals: * resistance increases with temperature * positive ions vibrate more * conduction electrons movement is impeded * positive temperature coefficient For intrinsic semiconductors: * resistance decreases with temperature * more charge carriers become available * negative temperature coefficient * much larger change in resistance /C than with metals * thermistors used as temperature sensitive component in a sensor V I + - - + High temp low temp

10. 4.4 Components and their characteristics Resistance and temperature For metals: * resistance increases with temperature * positive ions vibrate more * conduction electrons movement is impeded * positive temperature coefficient For intrinsic semiconductors: * resistance decreases with temperature * more charge carriers become available * negative temperature coefficient * much larger change in resistance /C than with metals * thermistors used as temperature sensitive component in a sensor V I + - - + High temp low temp V I + - - + High temp low temp