Glossary
Conductors
Materials, typically metals, that allow electric charge (electrons) to move freely throughout their volume.
Example:
Copper wires are excellent conductors because their electrons can easily flow, enabling electricity to power your devices.
Electric Field Lines
Visual representations used to map electric fields, where lines point in the direction of the field and their density indicates field strength.
Example:
Drawing electric field lines around a positive charge shows them radiating outwards, like spokes from a wheel.
Electric Fields
Invisible force fields surrounding charged objects, representing the force per unit charge that another charge would experience at any given point.
Example:
The Earth's gravitational field pulls objects down; similarly, an electric field around a charged balloon can make your hair stand on end.
Electrostatic Equilibrium
The state of a conductor where all charges are at rest, resulting in a zero net force on any charge within the conductor.
Example:
When a metal sphere is charged and then left alone, the charges will quickly redistribute until the sphere reaches electrostatic equilibrium, with all excess charge on its surface.
Insulators
Materials that do not allow electric charge to move freely, holding electrons tightly in place.
Example:
The rubber coating on an electrical cord acts as an insulator, preventing you from getting shocked.
Spherically Symmetric Charge Distribution
A charge distribution where the charge density depends only on the distance from a central point, making the electric field radially symmetric.
Example:
A uniformly charged balloon exhibits a spherically symmetric charge distribution, meaning the electric field outside it behaves as if all the charge were at its center.
Superposition Principle
The principle stating that the total electric field at a point due to multiple charges is the vector sum of the electric fields produced by each individual charge.
Example:
To find the electric field at a point between two charges, you calculate the field from each charge separately and then use the superposition principle to add them as vectors.
Test Charge
A hypothetical, tiny, positive charge used to measure the electric field at a point without significantly altering the field itself.
Example:
To map the electric field around a charged plate, you'd imagine placing a tiny test charge at various points and observing the force it would feel.
Vector Quantities
Physical quantities that possess both magnitude (size or strength) and direction.
Example:
When describing the wind, stating it's blowing at '15 mph North' makes it a vector quantity, unlike just saying '15 mph'.