What is "admittance"

Admittance \Ad*mit"tance\, n.

1. The act of admitting.

2. Permission to enter; the power or right of entrance; also, actual entrance; reception.

   To gain admittance into the house.
   --South.

   He desires admittance to the king.
   --Dryden.

   To give admittance to a thought of fear.
   --Shak.

3. Concession; admission; allowance; as, the admittance of an argument. [Obs.]
   --Sir T. Browne.

4. Admissibility. [Obs.]
   --Shak.

5. (Eng. Law) The act of giving possession of a copyhold estate.
   --Bouvier.

   Syn: Admission; access; entrance; initiation.

   Usage: Admittance, Admission. These words are, to some extent, in a state of transition and change. Admittance is now chiefly confined to its primary sense of access into some locality or building. Thus we see on the doors of factories, shops, etc. ``No admittance.'' Its secondary or moral sense, as ``admittance to the church,'' is almost entirely laid aside. Admission has taken to itself the secondary or figurative senses; as, admission to the rights of citizenship; admission to the church; the admissions made by one of the parties in a dispute. And even when used in its primary sense, it is not identical with admittance. Thus, we speak of admission into a country, territory, and other larger localities, etc., where admittance could not be used. So, when we speak of admission to a concert or other public assembly, the meaning is not perhaps exactly that of admittance, viz., access within the walls of the building, but rather a reception into the audience, or access to the performances. But the lines of distinction on this subject are one definitely drawn.

Admittance \Ad*mit"tance\, n. (Elec.) The reciprocal of impedance. [Webster 1913 Suppl.] ||

1580s, "the action of admitting," formed in English from admit + -ance (if from Latin, it would have been *admittence; French uses accès in this sense). Used formerly in senses where admission now prevails. Admissure was used in this sense from mid-15c.

alt. 1 The act of admit. 2 Permission to enter, the power or right of entrance. 3 Actual entrance, reception. 4 (context euphemistic hypocoristic English) The vulva, especially the labia majora. n. 1 The act of admit. 2 Permission to enter, the power or right of entrance. 3 Actual entrance, reception. 4 (context euphemistic hypocoristic English) The vulva, especially the labia majora.

1. n. the right to enter [syn: entree, access, accession]

2. the act of admitting someone to enter; "the surgery was performed on his second admission to the clinic" [syn: admission]

Admittance may refer to:

• Admittance, a measure of how easily a circuit allows an electric current to flow
• Admittance (geophysics), the small effects of atmospheric pressure on gravity
• Thermal admittance, a measure of the ability of a material to transfer heat (see thermal conductivity)

In electrical engineering, admittance is a measure of how easily a circuit or device will allow a current to flow. It is defined as the inverse of impedance. The SI unit of admittance is the siemens (symbol S). Oliver Heaviside coined the term admittance in December 1887.

Admittance is defined as

$$Y \equiv \frac{1}{Z} \,$$

where

The synonymous unit mho, and the symbol ℧ (an upside-down uppercase omega Ω), are also in common use.

Resistance is a measure of the opposition of a circuit to the flow of a steady current, while impedance takes into account not only the resistance but also dynamic effects (known as reactance). Likewise, admittance is not only a measure of the ease with which a steady current can flow, but also the dynamic effects of the material's susceptance to polarization:

Y = G + jB 

where

• Y is the admittance, measured in siemens.
• G is the conductance, measured in siemens.
• B is the susceptance, measured in siemens.
• j =  − 1

In geophysics, admittance describes the small effects of atmospheric pressure on earth gravity. Studies have also been carried out regarding the gravity of Venus. Admittance in geophysics takes atmospheric pressure as the input and measures small changes in the gravitational field as the output. Geophysics admittance is commonly measured in μGal/mbar. These units convert according to 1 Gal = 0.01 m/s and 1 bar = 100 kPa, so in SI units the measurement would be in units of;

$\frac{\mathrm{m}/\mathrm{s}^2}{\mathrm{Pa}}$ or $\frac{\mathrm{m}/\mathrm{s}^2}{\mathrm{N}/\mathrm{m}^2}$ or $\frac{\mathrm{m}^3}{\mathrm{N}\cdot \mathrm{s}^2}$ or, in primary units $\frac{\mathrm{m}^2}{\mathrm{kg}}$

However, the relationship is not a straightforward one of proportionality. Rather, an admittance function is described which is time and frequency dependent in a complex way.