Electric cells, also known as batteries, function as electrical power supplies by converting stored chemical energy into electrical potential energy. This process allows electricity to flow.
The Basic Principle
At its core, an electric cell has two terminals: a positive terminal and a negative terminal. Inside the cell, chemical reactions take place. These reactions cause a buildup of positive charges at the positive terminal and a buildup of negative charges at the negative terminal. This creates a difference in electrical potential, also known as voltage, between the two terminals.
How the Current Flows
When an external circuit (like a wire connected to a light bulb) is connected between the two terminals, the positive charges are compelled to move. Positive charges will flow from the positive terminal, through the external circuit, towards the negative terminal. This flow of positive charges is what we define as electric current. The current flows as long as the chemical reactions in the cell continue to produce the difference in electrical potential.
Key Components & Process Overview
Here's a quick summary of how it all works:
| Component/Process | Description |
|---|---|
| Chemical Energy | Stored within the materials of the electric cell. |
| Conversion | Chemical reactions convert the stored chemical energy into electrical potential energy. |
| Positive Terminal | Accumulates positive charges due to chemical reactions. |
| Negative Terminal | Accumulates negative charges due to chemical reactions. |
| External Circuit | The pathway (like a wire) through which current flows. |
| Current | The flow of positive charges from the positive to the negative terminal via the circuit. |
Practical Insights:
- Different Chemicals, Different Cells: The specific chemical reactions that occur vary depending on the type of cell (e.g., alkaline, lithium-ion, lead-acid). This leads to cells having different voltages and life spans.
- Discharge: As a cell provides current, the chemical reactions use up the reactants, eventually causing the cell to 'discharge' and no longer provide a useful current.
- Rechargeable Cells: Certain cells, like lithium-ion batteries, are designed with reversible chemical reactions that can restore the original chemical state of the cell when electricity is passed through them, thereby recharging them.
- Terminal Identification: The positive terminal is commonly marked with a "+" symbol, while the negative terminal is marked with a "-" symbol.
In Simple Terms
Imagine the positive terminal as a high place full of water, and the negative terminal as a low place. When you connect them with a hose, the water (positive charges) flows from the high place to the low place, creating a flow. The electric cell acts like a pump that keeps replenishing the water at the high point.
