values ​​characterizing the electric current

Ohm's law, unlike, for example, Coulomb's law, it is not a fundamental law of physics.It is of practical importance.
In nature there are substances, electrically conductive - conductors and conductive - dielectrics.
The conductors have free charges - electrons.In order to move electrons started in unison in one direction, it is necessary electric field, which "force" them to move from one end to the other conductor.
simplest way to create such a field may be an ordinary battery.If at the end of the conductor lack of electrons, it is indicated by a "+" if the excess is "-".Electrons have a negative charge always naturally flock to positive.So in Explorer is born an electric current, that is. E. The direction of movement of electric charges.To increase it,
is necessary to strengthen the electric field in the conductor.Or, as they say, to attach to the ends of the wire higher voltage.
electric current is usually denoted by the letter I, and stress - the letter U. is important to understand that the formula R = U / I only allows to calculate the resistance of the circuit, but it does not reflect the dependence of the resistance on the voltage and amperage.
But conductors, which are moving free electrons, can have different electrical resistor R. The resistance shows a countermeasure conductor material passing through it an electric current.It depends only on the geometrical dimensions of the conductor material and its temperature.
Each of these variables has its units: The Power of the current I is measured in amperes (A);The voltage U is measured in volts (V);Resistance is measured in ohms (ohms).

Ohm's law for subcircuit

In 1827 the German scientist Georg Ohm established mathematical relationship between these three values, and formulated it in words.So there was a law, named after its creator Ohm's law.His complete statement follows: "The strength of the current flowing through a circuit is directly proportional to the applied voltage and inversely proportional to the resistance of the circuit."
To avoid confusion in the output of the derivatives of formula, place the value of the triangle, as shown in Figure 2. Close your finger desired value.The relative position of the remaining shows what action to perform. formula for Ohm's Law looks like: I = U / R
Simply put, the higher the voltage, the stronger the current, but the greater the resistance, the current is weaker.