# The ammeter and measuring the electric current intensity

The electric energy is the cleanest source of energy as it does not pollute the environment, The electricity plays the important role in the daily life , It is used to light up our houses , factories , streets , It is used in operating some machines such as the radios , televisions , washing machines , irons , And the electric heaters , We can not imagine our life without the electric current .

### The electric current

The electric current is generated in the electric power stations that are away from our houses by hundreds or thousands of kilometers, The electric current is the electric negative charges flow ( the electrons ) through the conducting material ( as a metal wire ).

All the elements consists of the atoms which consist of the nucleus and the electrons , The nucleus is found in the center of the atom and it contains two types of particles which are the protons ( positively charges ) and the neutrons ( electrically neutral ) .

The electrons are very small particles which are negatively charged and they rotate around the nucleus ( due to the attraction force that is found between the electrons and the protons ), When the attraction force is weak or vanished, The electrons will leave the atom and they will become free.

The electric connecting wires are made up of metals characterized by presence of the attraction force between its protons and its electrons , where on connecting these wires with an electric source , an electromotive force is generated and the electrons are pumped in one direction and move in the wire ( conductors ) creating the electric current .

The atom is electrically neutral because the number of the protons ( positively charged ) in the nucleus equals the number of the electrons ( negatively charged ) that rotate around the nucleus , The nucleus is positively charged because it contains the protons ( positively charged ) and the neutral neutrons .

##### The current intensity

The current intensity is from the physical properties of the electric current , If you pass an electric current through a circuit and the lamp light up, the intensity of light is not determined by the number of electrons , but by the rate of the flow of electrons through a specific point in the wire.

The electric current intensity is the quantity in coulomb or the electric charges flowing through a cross-section of the conductor in one second, The current flowing through the conductor at the certain time interval is directly proportional to the charge quantity.

If a quantity of charge ( q ) coulomb flows through a conductor in a time ( t ) second, The measuring unit of the current intensity is Ampere , The measuring unit of the quantity of electricity is Coulomb , And the measuring unit of the time is the second .

Electric current intensity ( I )  =  Quantity of charge (q ) / Time in seconds ( t )

The ampere is the electric current intensity passing through the circuit when the charge of one coulomb passes through the given cross-section in one second, The coulomb is known as the charge transferred by the constant current of intensity one ampere in one second.

The apparatus used in measuring the electric current intensity is called the Ammeter which is connected in series in the electric circuits , The Ammeter has the symbol A in the electric circuit , The ammeter is not connected directly to the battery , because this damages it.

#### Uncut electric charger device

The uncut electric charger device ( uninterruptible power supply ) ( UPS ) , It is used to store the electric energy for a long or short period of time , where , it provides the electric devices with the electric current so as to continue operating when there is no current at home.

Electrical current , Potential difference , Electric resistance and Ohm’s law

Resistances connection ( series & parallel ) , Electric energy and Electric power

Ohm’s Law for the closed circuit , Relation between emf ( VB ) of an electric cell & voltage across its poles