Glossary
Charge (q)
A fundamental property of matter that can be positive or negative, responsible for electric and magnetic interactions.
Example:
An electron carries a fundamental negative charge, while a proton carries a fundamental positive charge.
Conservation
A fundamental principle stating that certain physical quantities, such as energy or charge, remain constant in a closed system, even as they transform from one form to another.
Example:
In a closed circuit, the total electrical energy supplied by the battery is conserved as it is transformed into heat and light by resistors.
Current (I)
The rate of flow of electric charge through a conductor. It is measured in Amperes (A).
Example:
When you turn on a flashlight, the flow of electrons through the bulb creates an electric current that makes it light up.
Electrical Energy (W)
The energy associated with electric fields and charges, representing the total work done by or on charges in a circuit.
Example:
A household appliance consumes electrical energy from the wall outlet, converting it into useful work like heating or motion.
Electrical Power (P)
The rate at which electrical energy is used or generated in a circuit. It is measured in watts (W).
Example:
A 100-watt light bulb has an electrical power rating of 100 W, meaning it converts 100 joules of electrical energy into light and heat every second.
Ohm's Law (V=IR)
A fundamental law stating that the voltage across a resistor is directly proportional to the current flowing through it, with resistance as the constant of proportionality.
Example:
If a 12V battery is connected to a 4Ω resistor, Ohm's Law tells us the current flowing will be 3 Amperes (I = V/R = 12V/4Ω).
Parallel Circuits
A circuit configuration where components are connected side-by-side, providing multiple paths for current flow, meaning the voltage is the same across all components.
Example:
Most household electrical outlets are wired in a parallel circuit, allowing multiple appliances to operate independently without affecting each other.
Resistance (R)
The opposition to the flow of electric current within a circuit element or material. It causes electrical energy to be converted into other forms, like heat.
Example:
A light bulb's filament has a specific resistance that limits the current flowing through it, causing it to glow brightly.
Resistivity (ρ)
An intrinsic material property that quantifies how strongly a specific material opposes the flow of electric current. It depends on the material type and temperature.
Example:
Copper has a very low resistivity, making it an excellent material for electrical wires, while rubber has a very high resistivity, making it an insulator.
Series Circuits
A circuit configuration where components are connected end-to-end, forming a single path for current flow, meaning the current is the same through all components.
Example:
Christmas tree lights where if one bulb goes out, the entire string goes dark, are often wired in a series circuit.
Systems
In physics, a system refers to a defined collection of objects or components that interact, possessing properties like mass and charge, and often having internal structures.
Example:
When analyzing a circuit, you can consider the entire circuit as a system of interconnected components, each with its own properties and interactions.
Voltage (V)
The electrical potential difference between two points in a circuit, representing the 'push' or energy per unit charge available to drive current.
Example:
A 9V battery provides a voltage of 9 volts, meaning it gives 9 joules of energy to every coulomb of charge that passes through it.