Voltage:
Definition:
“Voltage is the amount of work done per unit charge that makes the
electrical current flow in a circuit by pushing the electrons around against
electric field.”
Explanation:
The voltage between two ends of a path is the total
energy required to move a small electric charge along that path, divided by the
magnitude of the charge. Mathematically this is expressed as the line integral of the electric field and the time rate of change of
magnetic field along that path. In the general case, both a static (unchanging)
electric field and a dynamic (time-varying) electromagnetic field must be
included in determining the voltage between two points.
Historically this quantity has also been called
"tension" and
"pressure". Pressure is now obsolete but tension is still used, for
example within the phrase "high tension" (HT) which is commonly used
in thermionic valve (vacuum tube) based electronics.
Voltage is defined so that negatively charged objects
are pulled towards higher voltages, while positively charged objects are pulled
towards lower voltages. Therefore, the conventional
current in a wire or resistor always flows from higher voltage to
lower voltage. Current can flow from lower voltage to higher voltage, but only
when a source of energy is present to "push" it against the opposing
electric field. For example, inside a battery,
chemical reactions inside the battery provide the energy needed for current to
flow from the negative to the positive terminal.
Unit:
In mks
system it is measured in volts.
Formula:
Voltage
is determined by using the following formula,
V= IR
Measuring
instrument:
Voltage
is normally measured by an instrument called Voltmeter
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