Amperostat
Encyclopedia
An amperostat is a control
and measuring device used to keep constant the current flowing though electrolytic cell
s in coulometric titrations, disregarding changes in the load itself. Synonym is "galvanostat
". The amperostat respond to changes in the resistance
of the cell by varying its output potential: as Ohm's law
shows,
the variable system resistance
and the controlled voltage
are directly proportional, i.e.
where
thus, an increase of the load resistance implies an increase of the voltage the amperostat applies to the load. This device differs from common constant current sources by its ability to supply and measure
a wide range of current
s (from picoamperes to ampere
s) of both polarities.
Controller (control theory)
In control theory, a controller is a device which monitors and affects the operational conditions of a given dynamical system. The operational conditions are typically referred to as output variables of the system which can be affected by adjusting certain input variables...
and measuring device used to keep constant the current flowing though electrolytic cell
Electrolytic cell
An electrolytic cell decomposes chemical compounds by means of electrical energy, in a process called electrolysis; the Greek word lysis means to break up. The result is that the chemical energy is increased...
s in coulometric titrations, disregarding changes in the load itself. Synonym is "galvanostat
Galvanostat
A galvanostat is a control and measuring device capable of keeping the current through an electrolytic cell in coulometric titrations constant, disregarding changes in the load itself. A synonym is "amperostat"....
". The amperostat respond to changes in the resistance
Electrical resistance
The electrical resistance of an electrical element is the opposition to the passage of an electric current through that element; the inverse quantity is electrical conductance, the ease at which an electric current passes. Electrical resistance shares some conceptual parallels with the mechanical...
of the cell by varying its output potential: as Ohm's law
Ohm's law
Ohm's law states that the current through a conductor between two points is directly proportional to the potential difference across the two points...
shows,
the variable system resistance
Electrical resistance
The electrical resistance of an electrical element is the opposition to the passage of an electric current through that element; the inverse quantity is electrical conductance, the ease at which an electric current passes. Electrical resistance shares some conceptual parallels with the mechanical...
and the controlled voltage
Voltage
Voltage, otherwise known as electrical potential difference or electric tension is the difference in electric potential between two points — or the difference in electric potential energy per unit charge between two points...
are directly proportional, i.e.
where
is the electrical current that is kept constant
is the output control voltageVoltageVoltage, otherwise known as electrical potential difference or electric tension is the difference in electric potential between two points — or the difference in electric potential energy per unit charge between two points...
of the amperostat
is the electrical resistanceElectrical resistanceThe electrical resistance of an electrical element is the opposition to the passage of an electric current through that element; the inverse quantity is electrical conductance, the ease at which an electric current passes. Electrical resistance shares some conceptual parallels with the mechanical...
that varies
thus, an increase of the load resistance implies an increase of the voltage the amperostat applies to the load. This device differs from common constant current sources by its ability to supply and measure
Measure
- Legal :* Measure of the Church of England is a law passed by the General Synod and the UK Parliament equivalent of an Act* Measure of the National Assembly for Wales, a law specific to Wales passed by the Welsh Assembly between 2007 and 2011...
a wide range of current
Electric current
Electric current is a flow of electric charge through a medium.This charge is typically carried by moving electrons in a conductor such as wire...
s (from picoamperes to ampere
Ampere
The ampere , often shortened to amp, is the SI unit of electric current and is one of the seven SI base units. It is named after André-Marie Ampère , French mathematician and physicist, considered the father of electrodynamics...
s) of both polarities.