How do electricity electric current electrons move in wires, cables, and metals?

The movement of current in wires, cables, and metals is a fundamental physical phenomenon that involves the motion of electrons and the properties of conductive materials. Here is a detailed explanation of this process:

1. Concept of Free Electrons

In metals and conductive materials, there are a large number of free electrons. These free electrons are not bound to atomic nuclei and can move freely within the material. The presence of free electrons is the primary reason why metals are good conductors of electricity.

2. Effect of an External Electric Field

When a voltage (i.e., an external electric field) is applied across a conductive material, the free electrons are influenced by the electric field and begin to move directionally. The direction of the electric field determines the direction of electron movement. Typically, the electric field points from the positive terminal to the negative terminal, and electrons move in the opposite direction, from the negative terminal to the positive terminal.

3. Directed Movement of Electrons

Under the influence of the electric field, free electrons start to move directionally, forming a current. The direction of the current is defined as the direction of positive charge movement, which is opposite to the actual direction of electron movement. Therefore, when we say current flows from positive to negative, it actually means that electrons are moving from negative to positive.

4. Interaction with the Lattice

During their movement, free electrons collide with the lattice (atomic arrangement) of the material. These collisions scatter the electrons, changing their direction of movement and reducing their average velocity. This scattering effect is one of the sources of resistance.

5. Current Density

Current density (J) is the current per unit cross-sectional area and can be expressed by the formula:

J= I/A

where I is the current and A is the cross-sectional area of the conductor.

6. Ohm's Law

Ohm's Law describes the relationship between current, voltage, and resistance:

V=IR

where V is the voltage, I is the current, and R is the resistance.

7. Properties of Conductive Materials

Different conductive materials have varying conductive properties, which depend on their electronic structure and lattice structure. For example, copper and silver are excellent conductors because they have a large number of free electrons and low resistivity.

8. Effect of Temperature

Temperature has a significant impact on conductivity. Generally, as temperature increases, lattice vibrations in the material intensify, increasing the frequency of electron-lattice collisions and leading to higher resistance. This is why the resistance of conductors increases at higher temperatures.

9. Superconductivity

Under certain specific conditions, some materials can enter a superconducting state, where resistance drops to zero, allowing current to flow without any loss. Superconductivity typically occurs at very low temperatures, but recent research has discovered some high-temperature superconducting materials.

Summary

The movement of current in wires, cables, and metals is driven by the directed movement of free electrons under the influence of an external electric field. Electron interactions with the material's lattice cause resistance. The properties of conductive materials, temperature, and other factors all influence the efficiency of current transmission. Understanding these basic principles helps in better designing and applying conductive materials and circuits.