# Understanding Electrical Principles

• Electricity Basics:
• Electricity is the movement of electrons from one place to another.
• Molecules of solid conductive materials, such as metals, have free electrons that move around randomly. When an electric charge is applied, these electrons start to move in the same direction, creating an electric current.
• Current, Voltage and Resistance:
• Current is the rate of flow of charge. Measured in amperes (A).
• Voltage measures the energy carried by the charges. It’s the ‘push’ causing the charges to move. Measured in volts (V).
• Resistance opposes the flow of an electric current. High resistance means the current will decrease. Measured in ohms (Ω).
• Ohm’s Law:
• This law defines the relationship between voltage, current, and resistance. It states that the current through a conductor between two points is directly proportional to the voltage across the two points.
• The formula is V = I x R, where V represents voltage, I is current, and R shows the resistance.

# Circuit Elements and Their Properties

• Series and Parallel Circuits:
• In series circuits, components are connected in a line, end-to-end. If one fails, all fail.
• In parallel circuits, components are on separate branches. If one fails, others continue to work.
• Switches, Fuses and Circuit Breakers:
• A switch allows the current to flow when closed and stops it when open.
• Fuses and circuit breakers protect against overcurrent. A fuse melts and breaks the circuit when the current is too high. A circuit breaker trips and can be reset when the current exceeds a specified value.
• Capacitors and Inductors:
• Capacitors store electric charge and are used in filtering and energy storage operations.
• Inductors store energy in a magnetic field generated by the electric current passing through them.

# Power in Electrical Systems

• Electrical Power:
• Power (P) in an electrical circuit is the product of voltage and current, and it’s measured in watts (W): P = V x I.
• When considering resistance, power can also be calculated using the formulas: P = I² x R or P = V²/R.
• Efficiency of Electrical Devices:
• The efficiency of an electrical device is the ratio of useful power output to the total power input.
• Efficiency is commonly expressed in per cent by multiplying this ratio by 100. It is important in evaluating the performance of electrical systems and designing effective circuits.