PHY136H5 Lecture Notes - Multimeter, Joule Heating, Thermistor
Document Summary
When a battery is connected across a resistor (e. g. a light bulb or a heating element), current will flow through it. How much current is determined by a property of the resistor called (naturally) its resistance. The larger the resistance, the smaller the current. Among other things, it depends on what the object is made of. For example, identical cylinders of copper and rubber will have vastly different resistances to current flow. Copper is a good conductor whereas rubber is a good insulator. They differ in a property called the resistivity. Resistivity is a microscopic parameter which depends on the interaction between the current-carrying electrons and the lattice. The microscopic origin of resistivity is easy to picture. As an electron travels through a lattice, it will interact with, and be scattered by, the lattice ions. In other words, the lattice will interfere with the flow of the electrons. In general, resistivity is a function of temperature.
