Drift of Electrons and the Origin of Resistivity Drift of Electrons: Electrons are charged particles that are constantly in motion. While they are presen...
Drift of Electrons:
Electrons are charged particles that are constantly in motion. While they are present in conductors and semiconductors, they can also drift freely through space under certain conditions. This means that even though they are bound to specific atoms in a conductor, they can move independently.
Resistivity:
Resistivity is a measure of how strongly a material opposes the flow of electric current. It is defined as the ratio of the voltage applied to a conductor to the current flowing through it. In other words, it tells us how much the voltage needs to be increased in order to force a unit current through the conductor.
The Origin of Resistivity:
The main reason for the presence of resistance in a conductor is due to the fact that the electrons are not free to move randomly. When an electric current is passed through a conductor, these electrons are forced to flow in a specific direction. However, due to their charge, they are attracted to the oppositely charged electrodes. This creates a resistance to the flow of current, which results in the observed resistance.
Examples:
Resistive Materials: Materials like metals, such as copper and aluminum, are good conductors of heat and electricity. However, when a voltage is applied, the electrons in these materials are forced to move quickly, which creates resistance and slows down the current flow.
Non-Resistive Materials: Materials like semiconductors, such as silicon and germanium, are poor conductors of heat and electricity. This is because the energy required to push an electron through the material is larger than the energy gained when it is heated. As a result, electrons cannot easily move through non-resistive materials, and current can flow easily.
Variable Resistance: Some conductors exhibit variable resistance, meaning their resistance changes with the applied voltage. For example, certain materials like carbon have a high resistance at low voltages but a low resistance at high voltages. This property makes carbon a good conductor in certain applications, such as heating elements