Glossary
Alternating Current (AC)
Electric current whose direction of flow periodically reverses.
Example:
The electricity supplied to homes from wall outlets is alternating current.
Capacitors
Devices that store electrical energy in an electric field between two conductive plates separated by a dielectric.
Example:
A camera flash uses a capacitor to quickly discharge a burst of stored energy, illuminating the subject.
Circuit Diagram
A schematic representation of an electrical circuit using standardized symbols for components and connections.
Example:
Before building an electronic device, engineers first draw a detailed circuit diagram to plan the layout and connections.
Direct Current (DC)
Electric current that flows in only one constant direction.
Example:
A flashlight powered by batteries uses direct current to illuminate its bulb.
Electric Current
The rate of flow of electric charge, measured in Amperes (A).
Example:
When you turn on a device, electric current flows through its circuits, enabling it to function.
Electric Field
A region around an electric charge where a force would be exerted on another charged object.
Example:
The force that pulls a balloon charged by rubbing it on hair towards a wall is due to the electric field created by the charges.
Electric Flux
A measure of the number of electric field lines passing through a given surface.
Example:
When calculating the total charge inside a closed box, one would measure the electric flux through the box's surfaces.
Electric Power
The rate at which electrical energy is transferred or converted in a circuit, measured in Watts (W).
Example:
A 100W light bulb consumes electric power at a rate of 100 joules per second.
Gauss's Law
A fundamental law relating the electric flux through any closed surface to the total electric charge enclosed within that surface.
Example:
Using Gauss's Law, one can easily determine the electric field produced by a uniformly charged sphere or an infinitely long charged wire.
Inductors
Passive electrical components that store energy in a magnetic field when electric current flows through them, typically a coil of wire.
Example:
An audio crossover network uses an inductor to block high-frequency signals from reaching a woofer speaker.
Kirchhoff's Current Law (KCL)
States that the total current entering a junction (node) in an electrical circuit must equal the total current leaving that junction.
Example:
If 5A flows into a junction and 2A flows out through one branch, then Kirchhoff's Current Law dictates that 3A must flow out through the remaining branch.
Kirchhoff's Laws
A set of two fundamental laws (KCL and KVL) used for analyzing complex electrical circuits.
Example:
Engineers use Kirchhoff's Laws to design and troubleshoot intricate power distribution networks.
Kirchhoff's Voltage Law (KVL)
States that the algebraic sum of all voltages around any closed loop in a circuit must be zero.
Example:
When tracing a path around a series circuit, applying Kirchhoff's Voltage Law confirms that the sum of voltage drops across resistors equals the battery's voltage.
Ohm's Law
A fundamental law stating that the voltage across a conductor is directly proportional to the current flowing through it, given by V = IR.
Example:
Using Ohm's Law, you can calculate that a 12V battery connected to a 3Ω resistor will produce a current of 4A.
Parallel Resistors
Resistors connected side-by-side across the same two points in a circuit, where the voltage across each is the same, and their total resistance is calculated by the sum of their reciprocals.
Example:
Household outlets are wired in parallel resistors, ensuring that each appliance receives the full line voltage independently.
Resistance
The opposition to the flow of electric current in a circuit, measured in Ohms (Ω).
Example:
A toaster's heating element has high resistance, which causes it to heat up when current passes through it.
Resistors
Electrical components designed to oppose the flow of electric current, converting electrical energy into heat.
Example:
A light bulb uses a resistor (its filament) to glow by converting electrical energy into light and heat.
Series Resistors
Resistors connected end-to-end in a circuit, where the same current flows through each, and their total resistance is the sum of individual resistances.
Example:
In a string of old Christmas lights, if one bulb (a series resistor) burns out, the entire string goes dark because the circuit is broken.
Switches
Devices used to open or close an electrical circuit, thereby controlling the flow of current.
Example:
Flipping a wall switch completes a circuit, allowing electricity to flow to a light fixture.
Voltage
The electric potential difference between two points in a circuit, representing the energy per unit charge. Measured in Volts (V).
Example:
A 9-volt battery provides a voltage of 9V across its terminals, driving current through a connected circuit.
Voltage Sources
Components that provide electrical energy to a circuit, creating a potential difference.
Example:
A car battery acts as a voltage source to power the vehicle's electrical system.
Wires
Conductors that provide a pathway for electric current to flow with minimal resistance.
Example:
Copper wires are commonly used in household electrical systems to connect outlets and appliances to the power grid.