What is Electric Current?

 

 

Electric current is nothing but the rate of flow of electric charge through a conductor with respect to time. It is caused by drift of free electrons through a conductor to a particular direction. As we all know, the measuring unit of electric change is Coulomb and the unit of time is second, the measuring unit of current is Coulombs per second and this logical unit of current has a specific name Ampere after the famous French scientist André-Marie Ampere.

 

 

If total Q Coulomb charge passes through a conductor by time t, then current I = Q / t coulomb par second or Ampere.

 

For better understanding, let give an example, suppose total 100 coulombs of charge is transferred through a conductor in 50 seconds. What is the current?

As the current is nothing but the rate at which charge is transferred per unit of time, it would be ratio of total charge transferred to the required time for that.

 

Definition of Electric Current

While a potential difference is applied across a conductor, electrical charge flows through it and electrical current is the measure of the quantity of the electrical charge flowing through the conductor per unit time.

 

 

Measurement of Current

The most common method of measuring current is to connect an ammeter in series with the circuit that’s current to be measured. This is so because; the entire current flowing through the circuit must also flow through the ammeter also. The ideal internal resistance or impedance of an ammeter is zero. Hence, ideally there is no voltage drop across the ammeter connected in the circuit. A conventional analog ammeter consists of a current coil. Whenever current flows through this coil, it deflects from its position depending upon the amount of current flowing through it. A pointer is attached to the coil assembly; hence it points the current reading on the dial of the ammeter. For measuring alternating current, clip on meter or tong tester can also be used instead of conventional ammeter. In this ammeter a current transformer core is attached to the meter which can easily be clipped on the live current carrying conductor. Due to this arrangement, current in the circuit transforms to the secondary of the CT and this secondary current then measured on the dial of clip on meter without disturbing the continuity of the current unlike conventional ammeter.

 

 

Types of Current

There are only two types of electrical current, direct current and alternating current. We abbreviate them as DC and AC respectively. Concept of DC was developed before AC. But AC becomes most popular means of generating, transmitting and distributing of electric power. The direction of the flow of direct current is unidirectional, means this current does not alter its direction during flowing. Most common examples of DC in our daily life, are the current that we get from all kinds of battery system. But most popular form of electrical current is alternating current or AC. AC does have some advantages over DC for generating, transmitting and distributing and that is why the current we get from our electric supply companies, is normally alternating current.