# Electricity: Current and Circuit Symbols

## Electricity: Current and Circuit Symbols

## Understanding Current

**Electric current**refers to the flow of electric charge in a circuit.- It’s measured in
**amperes (A)**. - Current flows from the positive (+) side of the cell to the negative (-) side, this is known as
**conventional current**flow. - The two types of current are
**direct current (DC)**and**alternating current (AC)**. DC is a constant current that flows in one direction, whereas AC periodically reverses direction. **Ohm’s law**states that the current (I) through a conductor is directly proportional to the voltage (V) across it, provided the temperature remains constant. The formula is I = V/R.

## Understanding Circuit Symbols

- Circuit diagrams use
**symbols**to represent the different components. - A
**cell**is represented by one small and one larger parallel line. - A
**battery**comprises two or more cells, and is represented by multiple pairs of parallel lines. - A flat line or a line with three smaller lines branching off it illustrates a
**wire**. - An arrow pointing to a wire represents
**current**. - A
**resistor**is shown with a jagged line while a**variable resistor**has an arrow across it. - A
**lamp**is represented by a circle with a cross inside. - A
**diode**is a triangle pointing to a line. - A circle with an ‘A’ inside stands for an
**ammeter**, whereas a circle with a ‘V’ is a**voltmeter**. - A closed loop is a switch in the
**closed**position and a semi-open loop is a switch in the**open**position.

## Components of a Circuit

- The key components of a simple electric circuit are a
**power source**, a**load**(such as a light bulb or a fan), a**switch**, and**connective wires**. - The power source or
**cell**provides the voltage that drives the current around the circuit. - The
**load**provides resistance which controls the flow of current. - The
**switch**allows the current to be turned on or off by opening or closing the circuit. **Connective wires**conduct the current from the power source, through the load, and back to the power source.

Identifying and understanding these core topics around electricity will prove valuable for understanding more complex aspects of electrical circuits.