Electric Cell
We use electricity for many purposes to make our tasks easier, like lighting up our homes, pumping water, etc. An electric cell is a common source of electricity for simple items like torches, remote controls, and alarm clocks.
- An electric cell has a small metal cap on one side and a metal disc on the other.
- The metal cap is the positive (+) terminal.
- The metal disc is the negative (-) terminal.
- Inside the cell, there are chemicals stored. When these chemicals are used up, the cell stops producing electricity and must be replaced.
An Electric Circuit
A complete path through which electric current can flow from one terminal of an electric cell to the other is called an electric circuit.
graph TD
Cell((Electric Cell))
Switch["Switch (On/Off)"]
Bulb["Bulb (Load)"]
Cell -- Positive Wire --> Switch
Switch -- Connecting Wire --> Bulb
Bulb -- Negative Wire --> CellIf the bulb is connected correctly and the path is unbroken, the bulb lights up. This means the circuit is closed. If the path is broken (broken wire, loose connection, or filament break), current cannot flow. The circuit is open.
Fused Bulb
The thin wire inside the bulb that gives off light is called the filament. If a bulb does not glow even when properly connected, its filament may be broken. A bulb with a broken filament is said to be fused. A fused bulb interrupts the circuit because the path for current is broken inside it.
The Electric Switch
A switch is a simple control device used to either break the electric circuit or complete it.
- When the switch is ON (closed), the gap is bridged, and the circuit is complete.
- When the switch is OFF (open), there is an air gap, and current cannot flow.
Did you know? You can make a simple switch using two drawing pins, a safety pin, and some wire! The safety pin acts as the movable piece to connect or disconnect the two drawing pins.
Conductors and Insulators
Not all materials allow electricity to pass through them.
| Type | Definition | Examples |
|---|---|---|
| Conductors | Materials that allow electric current to pass through them easily. | Copper wires, Aluminium, Iron nail, Silver, Human body, Tap water. |
| Insulators | Materials that do not allow electric current to pass through them. | Eraser, Plastic, Wood, Rubber shoes, Dry air, Glass. |
Importance of Conductor & Insulator pairs: The electrical wires carrying current to our homes are made of copper (conductor) so current flows easily, but they are covered with plastic or rubber (insulator) so we don’t get electric shocks when we touch them! The handles of screwdrivers or pliers used by electricians normally have plastic or rubber covers for safety.