3.5.1.5 - Potential Divider Flashcards
If you had a 2Ω resistor and a 3Ω resistor what is the p.d across the 2Ω resistor?
2/5
Why is using a potential divider useful?
If you need a varying potential difference supply or one that is at a lower p.d. than the voltage source.
If you increase the resistance of a variable resistor what happens to the p.d. over the other resistor?
It decreases.
If resistance = 0 on the variable resistor, what is the p.d. over the other resistor equal to?
The total p.d.
Describe the resistance of a LDR
LDR’s have a very high resistance in the dark, but lower resistance in the light.
Describe the resistance in a NTC thermistor.
High resistance at low temperatures, but a much lower resistance at high temperatures.
What can both LDR’s and NTC thermistors be used for?
They can be used as one of the resistors in a potential divider, giving an out put voltage that varies with the light level or temperature.
When light shines on an LDR, describe the V over the other resistor.
When light shines on the LDR its resistance decreases, therefore the V over the other resistor increases.
What is the potential divider used for?
Used to supply a constant or variable potential difference from a power supply.