Series Circuit
add it up
Objective
Learn about series circuits and voltage dividers
Essential Keywords
- Voltage
- Current
- Series
- Voltage Divider
ATTENTION
We talked about Voltage being like a hill and the Battery puts the ball on top of the hill. We could also compare to items on a shelf. We can have the low shelf and a top shelf and anything in between. If one battery puts the ball on the first shelf, we can add a second battery to put it to the second shelf. A 4 battery pack is like a 4 shelf high system. Adding voltages on top of each other is a Series Circuit .
![4 AA battery](/sites/default/files/images/4AAbattery.jpg)
The typical Battery Pack puts the batteries in Series. A single AA battery is about 1.5 Volts. When we connect four in Series we get about 6 Volts.
Voltage Divider Circuit
Resistors can also be arranged in Series. In this case the value of the resistors adds up. So if each resistor is 100k then a series stack of five would be 500k. In a series circuit the current is the same in each resistor so from ohms law
V = I * R
You can see that the voltage is shared or divided among the resistors in the series stack. If they are all equal they will each have an equal voltage.
![Divider Schematic](/sites/default/files/images/VoltageDivider.jpg)
Here is the schematic diagram of the 4 batteries and 5 resistors in series.
we can implement this on a breadboard circuit and show how the voltage divides among the equal resistors
![Divider and meter](/sites/default/files/images/Divider5.jpg)
Here we have our 5 resistor voltage divider circuit implemented on a breadboard. We have used our electronic power supply to provide 5 Volts. A meter is connected to the top of the divider and the ground reading the full voltage that is about 5 Volts.
![divider 4 resistor](/sites/default/files/images/Divider4.jpg)
Here we have moved the meter connection down the series stack by one resistor. All of the resistors are equal so we have just stepped down 1/5 of the voltage leaving about 4 Volts.
![3 resistor divider](/sites/default/files/images/Divider3.jpg)
Similarly the next step gives about 3 Volts. The slight differences you are seeing from the expected voltage is due to the resistors not being perfectly equal.
![battery voltage divider](/sites/default/files/images/Batterydivider_0.jpg)
Here is a similar set up using the battery pack.
Project
First complete the measurements on the 5 equal resistor divider the next 2 steps. Then try different values of resistors to make your own divider. Make a divider circuit that gives us 1/10 of the voltage to provide a 10 x range for voltage measurements.