A-Level Physics: Magnetic Fields Flashcards

Vocabulary flashcards covering fundamental definitions, parameters, and key concepts related to magnetic fields from A-Level Physics exam paper notes.

Magnetic Field

A region of space where a magnetic pole, a current-carrying conductor, or a moving charged particle experiences a magnetic force.

Field of Force

A region of space where a particle experiences a force, such as a gravitational, electric, or magnetic force.

Magnetic Flux Density ($B$)

The force per unit length per unit current acting on a straight, current-carrying conductor placed perpendicular to the magnetic field.

Tesla ($\text{T}$)

The unit of magnetic flux density, defined as one newton per ampere per metre ($1\,\text{T} = 1\,\text{N}\,\text{A}^{-1}\,\text{m}^{-1}$) acting on a conductor carrying a current normal to the field.

Hall Voltage ($V_H$)

The potential difference developed across opposite faces of a current-carrying conductor or semiconductor when a magnetic field is applied perpendicular to the direction of current flow, given by $V_H = \frac{BI}{ntq}$.

Number Density ($n$)

The number of free charge carriers per unit volume in a conducting or semiconducting material.

Slice Thickness ($t$)

The dimension of a conducting or semiconducting slice measured parallel to the direction of the applied magnetic field in the Hall effect formula.

Velocity Selector

A device utilizing perpendicular uniform electric and magnetic fields to allow charged particles traveling at a specific velocity $v = \frac{E}{B}$ to pass undeviated.

Magnetic Flux ($\Phi$)

The product of the magnetic flux density $B$ and the cross-sectional area $A$ perpendicular to the magnetic field direction, given by $\Phi = BA$.

Specific Charge

The ratio of the charge of a particle to its mass ($\frac{q}{m}$).

Radius of Circular Trajectory ($r$)

The radius of the circular path described by a charged particle moving perpendicular to a uniform magnetic field, given by $r = \frac{mv}{Bq}$.

Lenz's Law

A law stating that the direction of an induced electromotive force (e.m.f.) or current is such that it opposes the change in magnetic flux causing it.