It seems like every holiday season I wait until the very last minute to do all of my Christmas shopping. Invariably, I'm left with no other option than to go to the local mall so I can hit all the stores at once. It's always the same situation: the place is packed and I have to fight the crowds to get from store to store. Perhaps this seems like a strange way to start a discussion on electrical resistance, but the two scenarios are actually very similar. You see, an electron trying to make its way through a wire is a lot like me trying to make my way through the mall. In fact, as we learn more about what causes electrical resistance, we'll see just how similar these situations really are.
In general, the word 'resistance' is used to describe an impeding force that acts against an object as it tries to get something done. When I was at the mall trying to make my way through the crowds, I kept bumping into people. Each one of these little collisions took some energy out of me as I fought against the impeding forces.
An electron flowing through a conductor faces the same challenges, but instead of people, it is impeded by the atoms in the material. The amount that an object impedes an electric current, which is the flow of electrons, is called itselectrical resistance, and it is measured in units of Ohms. The overall resistance of an object is affected by several factors, which we'll talk about in detail. The main thing to keep in mind is that any change that causes the electrons to have more collisions with the atoms will increase the resistance of the object.
