Energy is conserved in all circuits, for any complete circuit the sum of the emfs is equal to the sum of the potential differences.

Energy givers = energy takers.

In the diagram we can say that:                                        ε = pd₁ + pd₂ + pd₃ + pd₄.

Uses

In this potential divider the second resistor is a thermistor. When the

temperature is low the resistance (R₂) is high, this makes the output voltage

high. When the temperature is high the resistance (R₂) is low, this makes the

output voltage low. A use of this would be a cooling fan that works harder

when it is warm.

In the second potential divider the second resistor is a Light Dependant Resisitor.

When the light levels are low the resistance (R₂) is high, making the output voltage

high. When the light levels increase the resistance (R₂) decreases, this makes the

output voltage decrease. A use of this could be a street light sensor that lights up

when the surrounding are dark.