Glossary
Charge Carriers
Particles, typically electrons in metals, that are free to move within a material and are responsible for carrying electric charge.
Example:
In a copper wire, the free electrons act as charge carriers, allowing electricity to flow when a voltage is applied.
Conductor Polarization
The process where an external electric field causes the free charges within a conductor to redistribute, creating induced charges on its surfaces.
Example:
When a charged rod is brought near a neutral metal sphere, the sphere undergoes conductor polarization, with negative charges moving towards the rod and positive charges moving away.
Electric Field Inside a Conductor
The electric field within the interior of a conductor in electrostatic equilibrium, which is always zero.
Example:
If you're inside a charged metal box, you are safe from external electric fields because the electric field inside a conductor is zero.
Electric Field at Conductor Surfaces
The electric field lines that are always perpendicular to the outer surface of a conductor in electrostatic equilibrium.
Example:
When drawing electric field lines around a charged metal plate, you must ensure the lines meet the surface at 90 degrees, illustrating the electric field at conductor surfaces is perpendicular.
Electrostatic Equilibrium
The state of a conductor where all excess charge carriers have redistributed themselves and come to rest, resulting in no net motion of charge within the conductor.
Example:
When a metal sphere is charged, electrons quickly move until they are as far apart as possible on the surface, reaching electrostatic equilibrium where the electric field inside is zero.
Electrostatic Shielding
The phenomenon where a conducting enclosure protects its interior from external electric fields by redistributing charges on its outer surface to cancel the field inside.
Example:
A Faraday cage provides electrostatic shielding, protecting sensitive electronic equipment inside from external electromagnetic interference.
Equipotential Surface
A surface on which all points have the same electric potential. In electrostatic equilibrium, the entire volume and surface of a conductor form an equipotential surface.
Example:
If you map the electric potential around a charged metal sphere, you'll find that the surface of the sphere itself is an equipotential surface, meaning every point on it has the same voltage.
Ideal Conductors
Materials that allow electrons to move freely without any resistance, exhibiting zero electrical resistance.
Example:
While theoretical, a superconducting wire used in an MRI machine behaves like an ideal conductor at extremely low temperatures, allowing current to flow indefinitely without energy loss.
Non-uniform Charge Density
The condition where the concentration of excess charge on the surface of a conductor is not evenly distributed, being higher at sharp points or edges.
Example:
On a charged, irregularly shaped metal object, the non-uniform charge density means there will be more charge packed onto a sharp corner than on a flat side.
Sharp Protrusions
Points or edges on a conductor where the curvature is high, leading to a greater accumulation of charge and a stronger electric field nearby.
Example:
Lightning rods are designed with sharp protrusions to encourage charge accumulation and facilitate a controlled discharge during a thunderstorm.