3.5.1.5 - Potential Divider

Question 1

If you had a 2Ω resistor and a 3Ω resistor what is the p.d across the 2Ω resistor?

Answer 1

2/5

Question 2

Why is using a potential divider useful?

Answer 2

If you need a varying potential difference supply or one that is at a lower p.d. than the voltage source.

Question 3

If you increase the resistance of a variable resistor what happens to the p.d. over the other resistor?

Answer 3

It decreases.

Question 4

If resistance = 0 on the variable resistor, what is the p.d. over the other resistor equal to?

Answer 4

The total p.d.

Question 5

Describe the resistance of a LDR

Answer 5

LDR’s have a very high resistance in the dark, but lower resistance in the light.

Question 6

Describe the resistance in a NTC thermistor.

Answer 6

High resistance at low temperatures, but a much lower resistance at high temperatures.

Question 7

What can both LDR’s and NTC thermistors be used for?

Answer 7

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.

Question 8

When light shines on an LDR, describe the V over the other resistor.

Answer 8

When light shines on the LDR its resistance decreases, therefore the V over the other resistor increases.

Question 9

What is the potential divider used for?

Answer 9

Used to supply a constant or variable potential difference from a power supply.