1. The ratio of the effective value of a periodic function, such as an alternating current, to its average absolute value.

2. A factor that takes the shape of a coil into account when computing its inductance. Also known as shape factor.

The theoretical stress concentration factor for a given shape, for a perfectly elastic material.

A function which describes the internal structure of a particle, allowing calculations to be made even though the structure is unknown.

An expression used in studying the scattering of electrons or radiation from atoms, nuclei, or elementary particles, which gives the deviation from point particle scattering due to the distribution of charge and current in the target.