PCB Currents: How They Flow, How They React

4. Resistive Circuits

We learned in Chapter 1 that current is the flow of electrons. In a conductor, the electron in the valence shell is not held very tightly by its nucleus, so electrons can move through the crystalline structure hopping from one atom to another. It takes very little energy to move the electrons along through a conductor—but it does take some energy. The fact that it takes some energy means that there is some resistance to the flow of the electrons. In a conductor this resistance is pretty much accounted for within the atomic structure. It follows, therefore, that the more atoms there are in the immediate area of moving electrons, ...