﻿ Physical quantities of electric current

# Characteristics of electric current

Hello, dear readers of our website! We continue the cycle of articles devoted  to the beginning electricians. Today we will review physical quantities of electric current, types of connections and the Ohm's law briefly.

The unrolled chart of periodic alternating current.

For a start let's remember what types of current exist:

Alternating current (alphabetic reference of AC) - is developed thanks to magnetic effect. It is that current which we have in our dwellings. It has no poles because changes them many times in the second. This phenomenon (change of polyarnost) is called frequency, it is expressed in hertz (Hz). At present at us in network alternating current in 50 Hz is used (that is change of the direction happens 50 times a second). Two wires which enter the dwelling are called phase and zero as there are no poles here.

The direct current (alphabetic reference of DC) is that current which is received in the chemical way (for example batteries, accumulators). It is polarized and flows in determinate direction.

Main physical quantities:

Scheme of measurement of current intensity.

1. Potential difference (designation U). As generators affect electrons like the water pump, there is the difference on its plugs which is called potential difference. She says in volts (designation B). If we measure by the voltmeter potential difference on entrance and output connection of the electric device, then we will see on it indications 230-240 V. Obychno this size is called tension.
2. Current intensity (designation I). Let's say when connect the lamp to the generator, the electric circuit which passes through the lamp is created. The flow of electrons flows through wires and through the lamp. Force of this flow is expressed in amperes (designation A).
3. Resistance (designation R). Usually understand material which allows electrical energy to be transformed to thermal as resistance. Resistance is expressed in ohms (designation Ohm). Here it is possible to add the following: if resistance increases, current intensity decreases as tension remains to constants, and vice versa if to reduce resistance, current intensity will increase.
4. Power (designation P). Is expressed in watts (designation of W) - it defines amount of the energy consumed by the device which is connected to your socket at present.

## Types of connections of consumers

Conductors at inclusion in the chain can be connected with each other in the different ways:

1. Consistently.
2. In parallel.
3. In the mixed way

Connection at which the end of the previous conductor connects to the beginning of the following is called consecutive.

Connection at which all beginnings of conductors connect in one point, and the ends in another is called parallel.

The mixed connection of conductors represents set of series and parallel connections. Everything told by us in this article is based on the fundamental law of electrical equipment - the Ohm's law which says that current intensity in the conductor is directly proportional to applied voltage on its ends and is inversely proportional to resistance of the conductor.

This law is expressed as the formula so:

Current formula on the Ohm's law.

1. Sergey

Thanks! And the formula it is necessary to know it precisely.