Reinforcement (physics)

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Gain (Engl. Gain) is the magnification of a variable physical output over an input variable for a unique, possibly proportional relation. These can primarily be mechanical quantities, electrical quantities or light. The input and output variables are preferably of the same type. With an amplifier, for example an electrical amplifier or an optical amplifier , it is possible to increase the output power , for which energy must be supplied.

The term amplification is used both for direct quantities (e.g. direct voltage with the operational amplifier ) and for alternating quantities (e.g. with regard to the amplitude of a sinusoidal oscillation ). The gain generally depends on the properties of the input signal. For the technical application, the dependence on the frequency is particularly important.

For quantitative information, the gain factor is used as the ratio of output variable to input variable ; it can be a complex number :

If is, if there is a weakening, it is better to state the damping factor . Of these two quantities, the one that is greater than one in magnitude is used, so that its magnitude has a positive logarithm.

Often a gain is also given as a logarithmic quantity . For similar sizes on which the power depends on the square, z. B. electrical voltages, currents or sound pressures, the gain is formed using the decadic logarithm with the auxiliary unit Bel ( unit symbol B) or using the natural logarithm with the auxiliary unit Neper (unit symbol Np). For example, for effective values of the voltage is

See also

Individual evidence

  1. a b DIN 40148-1 Transmission systems and two- port systems - terms and sizes
  2. DIN EN 60027-3; Formula symbols for electrical engineering: Logarithmic and related quantities and their units