As electrons move through a load in an electric circuit (devices like a LED, buzzer, motor, etc.), they experience resistance (even through the wire itself), which corresponds to a drop in energy . This drop in energy is referred to as a voltage drop.  Resistance hinders the flow of electrons, even in the water itself.  You can think of resistance as the friction between the water and the pipe along the inside of the pipe.

The pipe, just like the wire, has a certain diameter and length. The longer the wire, the more resistance the electron will encounter, just as with a long pipe of water. If you increase the pipe diameter, more water will flow through it. The thicker the wire, the more current flows through it. The amount of resistance the charge encounters also depends on what the wire is made out of. Certain materials are more electrically conductive than others, with silver, copper and gold being at the very low end of electrical resistance (which is why most wires are made from copper, which is the least expensive of the three).

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It’s easy to find the resistance of objects using a simple mathematical equation that relates the length of the wire, the cross-sectional area, and the resistivity of the material. Here’s an example of how to do it:

Click here to go to your next lesson on Resistance over Distance.

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