With the concept of "voltage" all of us have to face almost every day, because the scope of its use is not limited only to appliances.This lightning in the rain, and sparks on a plastic comb and clothing made from synthetic fabrics and so on.
dry academic language gives the following definition of this phenomenon: the electrical voltage - a physical quantity indicating the value done by the charge at 1 C (Coulomb)operation.Pendant, in turn, indicates the amount of charge for the missed conductive material in 1 second with a current of 1 A.
also permitted another definition, according to which an electrical voltage is the ratio of work performed by an electric field to move the test (test) charge between two points, the numerical value of the charge.At the same time it is assumed that the charge transfer does not affect the potential difference (voltage does not change), and the trajectory of motion can be ignored.In a formula the definition is written as follows:
U = A / q,
where U - voltage, A - work, q - charge.
to remember what the measured voltage, there is no need for memorization, because tip is always at hand, since all the power sources specified voltage and its dimension: it is enough to look at any battery.Unit - V (B, V).
terms "voltage" chain AC and DC differ.In alternating current, characterized by periodic sine wave passing through the zero mark is not used for calculating the instantaneous and rms value.This is possible thanks to the fact that his work with the active linear load numerically corresponds to a constant voltage.
Those who had a chance to deal with three-phase motors, certainly noticed a strange entry in the passport characteristics.There through the stroke indicates two voltages such as 220/380 V. No misprint no, really, the equipment is able to work on two different current values.Where does the network 380 can take 220?It turns out that the voltage can be either phase or linear, depending on the measurement method.Phase determined by measuring the difference between each phase and neutral wire, and linear - between the phase conductors.By connecting the load circuit in the triangle, you can get the equality of line and phase voltages and for the scheme "star" phase in 1.73 times less linear.
for voltage measurement using a special device - a voltmeter.Its main feature - is the need to connect tokosnimayuschih probe parallel to the load.High internal resistance does not introduce distortion shunt.That is why, for example, in domestic use may be a direct connection to an outlet (unlike ammeter includes open circuit).
But let three-tier formula academics and see what exactly is "the electric current", in simple human language.Thus, the difference of charge (potential) between any two points of a conductor or an electric field.The source, causing the movement of electrons through a conductor (generator, battery), creating at one end of their surplus, but on the other - a disadvantage.Accordingly, the value of the charges is also different.It is enough to connect the dots any conductive medium, and there will be an electric current - the movement of charged particles, which tends to neutralize this difference.In other words, the nature of power implies pursuit of atoms to a stable state, a violation of the magnetic fields of the generator.Stress can exist without power if the resistance between the points is great.This explains the fact that the batteries are not familiar "fight the current."
