6.10 The Potential Divider

Question 1

What is a potential divider?

Answer 1

A circuit with a voltage source and a couple of resistors in series
The potential difference across the voltage source is split across the resistors in the ratio of the resistances

Question 2

What can you use potential dividers for?

Answer 2

To supply a potential differences across between zero and the potential difference across the power supply

Question 3

How do you calculate the output voltage of a potential divider?

Answer 3

Vout = R2/(R1 + R2) x Vs

Question 4

How do you vary Vout in a potential divider?

Answer 4

Replace the other resistor (not Vout) with a variable resistor (e.g. a light resistor or a thermistor)

Question 5

How does the resistance of light-dependent resistors vary in different light levels?

Answer 5

• in the dark, LDRs have high resistance
• in the light, LDRs have low resistance

Question 6

How does the resistance of NTC thermistors vary in different heat levels?

Answer 6

• at low temperatures, resistance is high
• at high temperatures, resistance is low

Question 7

What is a potentiometer?

Answer 7

A potentiometer has a variable resistor replacing R1 and R2 of the potential divider
You move a slider to adjust the relative sizes of R1 and R2