Circuit devices LDR + THERMISTOR

What is an LDR?

Light dependent resistor

What does an LDR do?

Resistor that is dependant on the intensity of light

How are LDRs used?

Automatic night lights

How do LDRs work?

Bright light = resistance falls
Darkness = resistance is highest

What is an thermistor?

Temperature dependant resistor

What does a thermistor do?

Resistance decreases when temperature increases

How are thermistors used?

Temperature detectors

How do thermistors work?

Hot conditions = resistance drops
Cool conditions = resistance goes up

What are sensing circuits?

They're used to turn on or increase the power to components depending on the conditions that they are in

In a sensing circuit why do the fixed resistor and the fan have the same potential difference?

They're connected in parallel

What happens to the sensing circuit when the room gets hotter?

The resistance of the thermistor decreases and it takes a smaller share of the potential difference from the power supply - making the fan goes faster