# Electricity: Circuits

## Electricity: Circuits

• An electric circuit is formed when there is a complete path allowing the electric charges to flow from the power source, through the wires, to the device (load), and then back to the source.
• In a series circuit, all the components are connected one after another in a closed path, forming a single path for the electricity to flow. If one component fails, the whole circuit stops working.
• In a parallel circuit, components are connected along separate branches. If one component fails, electricity can still pass through other branches - so not all components of the circuit will stop working.
• The current (measured in amperes/A) is the same at all points in a series circuit, while it splits up in a parallel circuit and the total current equals the sum of the currents through each branch.
• The total resistance in a series circuit is the sum of all individual resistances. In a parallel circuit, the total resistance is always less than the smallest individual resistance.
• Ohm’s Law relates voltage (V), current (I), and resistance (R) in a circuit: V = I * R.
• Power (P) is calculated by the formula: P = I * V.
• Electric potential energy (or electric potential), measured in volts (V), refers to the amount of work needed to move a unit charge from a reference point to a specific point inside the field without producing any acceleration.
• The Conservation of Charge principle states that charge cannot be created or destroyed in an isolated system.
• Static electricity is built up when electrons are transferred from one material to another. This can result in an electrical discharge if a conductive path is provided.
• Electrical safety relies on the correct use of insulation, earthing, fuses, and circuit breakers. The earth wire provides a safe route for the current to flow if there is a fault. Fuses and circuit breakers provide a break in the circuit if the current becomes too great.
• The energy transferred by a conducting material depends on its electrical properties, such as its resistivity. The energy transferred is equal to the product of the potential difference across the conductor and the charge flowing through it. This relationship is sometimes known as Joule’s law: E = V * Q.