Dissipation factor

The loss factor (English: dissipation factor, abbreviated DF) describes in physical oscillations of different nature, including in electrical engineering and the rheology, the ratio of the lossy to lossless real part imaginary part of a complex quantity. The loss factor is equal to the tangent of the loss angle between the complex size and its imaginary part.

Electrical Engineering


The loss factor indicates how large are the losses in electrical components such as inductors and capacitors, or in the propagation of electromagnetic waves in matter ( eg, air). With "loss" here is meant the energy that is electrically or electromagnetically lost and, for example, into heat (dissipation ). These losses by the electromagnetic wave is attenuated.

For a more detailed illustration of the loss factor is considered a capacitor, which is connected to a voltage source with a sinusoidal voltage waveform over time. In such a condenser, a phase shift between voltage and current:

  • An ideal capacitor having no losses, has a phase shift of ( radians)
  • In a real capacitor which has losses, the phase shift of the loss angle is less than:

Resonant circuit

As loss factor d ( damping; dissipation factor DF in English ) is also the inverse of the quality factor Q is in resonant circuits and filters:

See also coil quality.


In the rheology of the loss factor refers to the ratio between the loss modulus ( imaginary part) and storage modulus ( real part ):

  • The higher the loss factor, the more approaches the behavior of a sample of the ideal - viscous liquid with Newtonian flow behavior at
  • The lower the loss factor, the more the behavior is a sample to that of a perfectly elastic solid
  • Wave
  • Rheology