1. Conductors and Insulators:
Materials can be classified into conductors and insulators based on their ability to allow the flow of electric current. Conductors, such as metals, have loosely held outermost electrons known as free electrons, which are easily dislodged from their atoms. Insulators, on the other hand, have tightly bound electrons that are difficult to move.
2. Potential Difference (Voltage):
For electricity to flow, there must be a potential difference, also known as voltage, between two points in a circuit. Voltage represents the electrical pressure or driving force that causes electrons to move.
3. Electron Movement in Conductors:
When a conductor is connected to a voltage source, such as a battery, the voltage creates an electric field within the conductor. This field exerts a force on the free electrons, causing them to break away from their atoms and start moving.
4. Electron Drift:
The movement of free electrons in a conductor is called electron drift. These electrons, driven by the electric field, drift towards the positive terminal of the voltage source.
5. Current and Resistance:
The flow of electrons constitutes an electric current. The strength of the current depends on the number of free electrons, their mobility, and the resistance of the conductor. Resistance represents the opposition to the flow of current and can be influenced by factors like the material's resistivity and the conductor's length and cross-sectional area.
6. Complete Circuit:
For a continuous flow of electricity, there needs to be a complete circuit. This means there must be a closed pathway for the electrons to travel from the negative terminal of the voltage source, through the conductor, and back to the positive terminal.
7. Conventional Current vs. Electron Flow:
Historically, electric current was defined based on the movement of positive charges, even though electrons are the actual charge carriers. This convention led to the term "conventional current," which assumes the flow of positive charges from the positive terminal to the negative terminal. In reality, it is the negatively charged electrons that move in the opposite direction.
In summary, electricity flows due to the movement of free electrons in conductive materials. When a potential difference is established between two points in a circuit, electrons are prompted to drift towards the positive terminal, creating an electric current. This flow of electrons continues as long as there is a complete circuit and a source of voltage.
