Thermodynamics backgrounder
Visualization Even with perfect eyesight and the best optical microscope, observing the movements of atoms and molecules is impossible. The movement occurs on the scale of picometers and at frequencies measured in terahertz. At the atomic level, those constant and slight movements will disrupt any uninterrupted path an electron might try to take through the lattice, causing a collision with another electron, and a significant change in direction of movement. These disruptions are the basis for resistance. Consider a game of pool or billiards: imagine taking a shot while all of the balls, the pockets, the bumpers, and even the table move and vibrate in every direction. In this analogy, the pool balls are electrons, and the pool table is the crystalline lattice structure of the metal. Just as the balls in the games wouldn’t follow predictable paths, electrons will not either. Unlike the sixteen pool balls on the table, there are far more electrons in one pool ball than there are pool balls in the world (perhaps ). So the pool table we need to visualize has a zillion balls on the table. The ball you strike with a cue will cause bulk motion in the direction of your
This AI imagined view of the copper grains that might exist in copper metal. Electrons experience a bit more resistance at grain boundaries.
pool cue, but the first ball you strike won’t go very far before a collision with another ball. Similarly, electrons suffer so many collisions per second that even in high speed circuits, an individual electron moves along a copper trace approximately as fast as your fingernails grow.
Electron movement and resistance As electrons travel through a crystalline lattice in the presence of an electric field, there is no predictable path for any single electron. This randomness
20
Powered by FlippingBook