To start, we need to define current and voltage:
- Current is the rate (or speed) at which the electrons are flowing through the circuit and is measured in amperes (Amps).
- Voltage is technically the electrical potential difference between the beginning and end of a circuit….or simply, the force at which the current travels through the circuit. Voltage is measured in Volts (joules/coulomb).
We are going to start with the simple circuit we created in a previous post (connect the alligator clip to negative side of battery, then connect to knife switch, knife switch to lamp holder, lamp holder to positive side of battery).
Now let’s make some modifications and create a parallel circuit. In a parallel circuit, the voltage stays constant in each branch of the circuit.
Creating a Parallel Circuit
Using our simple circuit with the knife switch in the upright position, we are going to add another load (light) and create a parallel circuit.
- Take a wire with alligator clips and attach to one side of the existing lamp holder.
- Using a separate wire, attach one end to the other side of the existing lamp holder (*note: there will be 2 clips attached to each side of the existing lamp holder).
- Take the ends of the two wires that are free and clip one to each side of a new lamp holder with light bulb. When the knife switch is closed, both lights illuminate.
In a parallel circuit, the voltage stays constant in each branch of the circuit. So, using a 1.5V battery, both bulbs are receiving 1.5V of electricity. This is the reason both light bulbs have the same brightness. If you measured the current, you will find that the current is divided into each branch. Therefore, if 10 amps of current were flowing through the circuit, each light (or branch of the parallel circuit) would be receiving 5 amps of electricity. Adding the amount of current in each branch together, will give the total amount of current introduced into the circuit.