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Parallel Circuits, Hazard Lights

A parallel circuit is a closed electrical circuit in which the current is divided into two or more paths and then returns through a common path to complete the circuit.

A parallel circuit has alternate paths through which current can flow.


In a parallel circuit, the electrical current to each element (light bulb, etc.) in the circuit is separate, so if one element was to burn out, the other resistors would still have power. Also if you add an extra element, the other elements will still have the same amount of voltage as before. If you remove an element, the other elements will also still have the same amount of voltage as before. We know this because of the following rules that apply to parallel circuits.

V= voltage R= resistance I = current
1. The potential drops of each branch equals the potential rise of the source.

V(total) = V (1) = V (2) = V (3) = …

2. The total current is equal to the sum of the currents in the

I (total) = I (1) + I (2) + I (3) = …

3. The inverse of the total resistance of the circuit is equal to the sum of the inverses of the individual resistances.

1/R (total) = 1/R (1) + 1/R (2) + 1/R (3) + …


You are driving back from a Christmas ski holiday at night. It is pitch black out and you get a flat tire. You manage to get the car pulled over halfway onto the shoulder and then turn on your hazard lights. You jump out of your car and a semi-truck roars past you. When you get over to the front passenger side of the car to analyze the flat you notice that the front passenger hazard light had burnt out. Luckily cars are designed with safety in mind. With the hazard lights run in parallel the driver-side hazard light still works, allowing the semi-truck to see you on the side of the road.


What are other examples of parallel circuits you come in contact with everyday?

Answer: Parallel circuits are everywhere, a few could be your household lights, courtesy light in your vehicle, and street lights outside your house.

more basic parallel circuit problems

LRC parallel circuits problems

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Gregory Shepertycky

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