Physics Grade 9: Electric Fields and Current

A set of vocabulary flashcards based on the Grade 9 Physics lessons on Electric Fields (Part 1 and 2) and Electric Current.

Electric Field

The electric force per unit test charge.

Vector Field

A field that shows both magnitude and direction, such as wind velocity maps.

Scalar Field

A field where only a number is assigned to each point in space, such as temperature maps.

Test Charge

A very small positive charge used to measure the electric field without affecting it.

Principle of Superposition

The principle used to calculate the net electric field from multiple charges.

Electric Field Lines

Lines that begin on positive charges and end on negative charges (or at infinity) to indicate the strength and direction of the field.

Electrostatic Equilibrium

A state where the electric field at the surface of a conductor is perpendicular to the surface.

Curvature

Regions where excess charge on a conductor concentrates most.

Uniform Electric Field

A field in which the magnitude and direction are the same at all points, represented by parallel and evenly spaced lines.

Capacitor

A device used to store electrical energy due to the separation of opposite charges.

Electric Current

The flow of charge through a wire per unit time, calculated as $I = \frac{\Delta Q}{\Delta t}$.

Ampere

The SI unit of electric current.

Drift Velocity

The average speed of electrons moving through a conductor.

Collisions

Friction-like interactions between electrons and metal ions that cause electrons to reach a constant drift velocity.

Resistance

The opposition to the flow of electric current in a material, calculated as $R = \frac{\rho L}{A}$.

Resistivity

An intensive property that depends on the type of material and affects resistance.

Conventional Current

The flow of charge defined as being in the same direction as the electric field.