Topic 2 Circuit Devices G***g Flashcards
What is the LDR and what is it dependent on
A resistor that is dependent on the intensity of light
When does resistance fall
In bright light
When is resistance the highest in. An LDR
In darkness
What are LDR resistors used for
Automatic night lights, outdoor lighting and burglar detectors
What is a thermistor dependent on
Temperature
Hot conditions
Resistance drops
Cool conditions
Resistance goes up
What are thermistors used as
Temperature detectors
E.g car engine
Electronic thermostats
what are sensing circuits used for
To turn in or increase the power to components depending on the conditions that they are in
Why will a fan and fixed resistor always have the same potential difference
Because they are connected in parallel
The pd Of the power supply is shared out between the thermostat in the loop made up of the fixed resistor and the fan according to what
They’re resistances
the bigger a components resistance the more potential difference it takes
As the room gets hotter the resistance of the thermostat decreases and takes a smaller share of the potential difference of the power supply so what happens to the fan
The potential difference across the fixed resistor and the fan rises making the fan go faster
Why would a bulb connected in parallel to an LDR get brighter as the room got darker
The potential difference across both the LDR and the bulb will be high when it’s dark and the LDLs resistance is high
the greater the potential difference across a component the more energy gets in
