1. Voltage Divider

2. Series Circuits Take a series circuit with two resistors
Since each is the same resistance, they use up the same amount of voltage, 6V
Therefore the voltage at point A is 6V

3. Series Circuit
We can rearrange the circuit as shown on the right

4. Series Circuit
And then simplify it once more

5. Series Circuit =

6. Voltage Divider
It doesn’t matter the amount of resistance, if they are equal they use the same voltage
The voltage at A in this case is still 6V

7. Voltage Divider
By adjusting the ratio of the resistors, we change how much voltage each one “uses up”
The resistance at A is significantly higher now since the second resistor will need much more voltage

8. Voltage Divider
The resistance at A will now be significantly lower since the first resistor will use up most of the voltage
By altering the ratio of resistors we can alter the voltage at A

9. Voltage Divider
Suppose we replace the top resistor with a sensor that can change resistance
In this case a light sensor, photoresistor, that operates from 1k – 10k based on light
By measuring the voltage at A we can determine the amount of light in the room

10. Complete the “Sensors in a Circuit” Lab