Magnetic flux and flux linkage (A-level only) Flashcards – AQA A-level Physics (7408)

What does magnetic flux through a surface measure?

The magnetic field passing through the surface.

What is the SI unit of magnetic flux?

The weber (Wb).

What is the magnetic flux through a surface of area $A$ in a uniform field of flux density $B$ normal to the surface?

$\Phi = BA$

What is flux linkage?

The total magnetic flux linked with the turns of a coil.

What is the flux linkage of a coil with $N$ turns if each turn links the same flux $\Phi$?

$N\Phi$

A rectangular coil of area $A$ is in a uniform field of flux density $B$. The angle between the field and the normal to the coil is $\theta$. What is the flux through each turn?

$\Phi = BA\cos\theta$

A rectangular coil has $N$ turns and area $A$. It is in a uniform field of flux density $B$, at an angle $\theta$ to the coil’s normal. What is its flux linkage?

$N\Phi = BAN\cos\theta$

For a rotating coil in a uniform magnetic field, which field orientations give the greatest and zero flux linkage?

Greatest: field normal to the coil’s plane.
Zero: field parallel to the coil’s plane.