IB Physics Topic D - Fields Key Definitions

Atmospheric drag is the resistance experienced by an object moving through a planet’s atmosphere.

Centripetal force is a force that acts on a body moving in a circular path and is directed towards the centre around which the body is moving.

Angular momentum is conserved unless an external torque acts on the system.

Density refers to how much mass is contained in a given volume of the medium.

Eddy currents are loops of induced current that form in conductors exposed to a changing magnetic field.

An electric field is a region of space where a charge experiences a force.

The electric field strength $E$ is defined as the force per unit charge experienced by a small positive test charge $q$.

Electric potential is the amount of work done per unit charge in bringing a small positive test charge from infinity to a point in an electric field.

Electric potential difference, or voltage, is the energy per unit charge required to move a charge between two points in an electric field.

Electric potential energy is the energy stored in a system of charged particles due to their positions relative to each other.

Equipotential surfaces are imaginary surfaces where the gravitational potential is the same at every point.

Escape velocity is the minimum speed an object must have to break free from a gravitational field without any additional energy input.

Faraday’s law states that a changing magnetic flux through a loop induces an emf (electromotive force) in the loop.

The gravitational field strength ($g$) at a point is defined as the force per unit mass experienced by a small test mass placed at that point.

A gravitational field is a region of space where a mass experiences a gravitational force.

Gravitational potential ($V_g$) is the work done per unit mass to bring a small test mass from infinity to a point in a gravitational field.

Gravitational potential energy is the energy stored due to the position of an object in a gravitational field.

Lenz’s law states that the direction of the induced emf is such that it opposes the change in magnetic flux that produces it.

This principle ensures the conservation of energy.

Magnetic flux $\Phi$ quantifies the amount of magnetic field passing through a given surface.

The strength of a magnetic field, measured in tesla (T). It fixes the size of the force a field exerts on a moving charge or a current-carrying wire.

Orbital speed is the speed an object must have to maintain a stable circular orbit around a larger mass.

Work is defined as the product of the force applied to an object, the displacement of the object, and the cosine of the angle between the force and the displacement.