What is Current in Electronics | Types of Electric Current, Formula, Examples
Learn What is Current in Electronics – Types of Electric Current, Formula, Examples Explained in Detail.
Here we Learn What is Current in Electronics – Types of Electric Current, Formula and Examples Explained in Detail.
What is Current?
Charge is mobile and can flow freely in certain materials, called conductors. Metals and a few other elements and compounds are conductors. Example – Copper, Aluminum and Most Metals.
Materials that charge cannot flow through are called insulators.
Examples – Air, glass, most plastics, and rubber are insulators.
And then there are some materials called semiconductors, that seemed to be good conductors sometimes but much less so other times.
Examples – Silicon and Germanium.
There is a force between charge, the potential for work, and thus a voltage. Now we connect a conductor between them, a metal wire. On the positively charged sphere, positive charges rush along the wire to the other sphere, repelled by the nearby similar charges and attracted to the distant opposite charges.
The same thing occurs on the other sphere and negative charge flows out on the wire. Positive and negative charges combine to neutralize each other, and the flow continues until there are no charge differences between any points of the entire connected system.
There may be a net residual charge if the amounts of original positive and negative charge were not equal, but that charge will be distributed evenly so all the forces are balanced. If they were not, more charge would flow. The charge flow is driven by voltage or potential differences.
After things have quieted down, there is no voltage difference between any two points of the system and no potential for work. All the work has been done by the moving charges heating up the wire.
Electric Current Definition
The flow of charge is called electrical current. It is measured in amperes (a), amps for short (named after the French Mathematician and Physicist, André-Marie Ampère, who worked mostly with magnetic effects.)
What is Ampere?
An ampere is defined as a flow of one Coulomb of charge in one second past some point.
While a Coulomb is a lot of charge to have in one place, an ampere is a common amount of current; about one ampere flows through a 100 watt incandescent light bulb, and a stove burner or a large motor would require ten or more amperes.
On the other hand low power digital circuits use only a fraction of an ampere, and so we often use units of 1/1000 of an ampere, a milliamp, abbreviated as ma, and even 1/1000 of a milliamp, or a microamp, µa
Direction of Current
Current has a direction, and we define a positive current from point A to B as the flow of positive charges in the same direction. Negative charges can flow as well, in fact, most current is actually the result of negative charges moving. Negative charges flowing from A to B would be a negative current, but, and here is the tricky part, negative charges flowing from B to A would represent a positive current from A to B.
The net effect is the same: positive charges flowing to neutralize negative charge or negative charges flowing to neutralize positive charge; in both cases the voltage is reduced and by the same amount.
Types of Electric Current
Electric Current are of 2 Types:
1. Alternating Current (AC)
Electrical current whose direction and value keeps changing is known as Alternating Current (AC). The value of AC current in one direction increases from ZERO to Maximum and fall down to ZERO and then in opposite direction it increases from ZERO to Maximum again and come back to ZERO.
Due to this increase in both directions, the graph of AC looks like a Wave. This is called sine wave. In Alternate Current or AC, 50 such cycles or waves come in ONE Second. One side of AC is PHASE and the other side is NEUTRAL.
2. Direct Current (DC)
DC or Direct Current is the flow of electric charge in one direction. This is called unidirectional flow of electric charge. DC current is produced by devices like battery, thermocouple, solar cell, dynamo etc. DC current is also called galvanic current.
How is Electric Current Measured?
Electric current is measured using an Ammeter. Milliammeters are used to measure smaller current in milliampere. Microammeters are used to measure smaller current in microampere.
What is the SI Unit of Current?
The SI unit of current is ampere (Unit Symbol = A).
1 Ampere = 1 Coulomb of charge passing a given point per second.
Electric Current Formula
As mentioned above, the rate of flow of charge through a conductor is called electric current. It is related to the resistance of the material and the voltage applied to move the charge. It is measured in amperes (A).
Electric current = Voltage / Resistance
The Formula is: I = V/R; Where:
- I: Electric Current
- V: Voltage
- R: Resistance of the material
Example-1) A wire is connected to a battery with a voltage of 9 V. Its resistance is 2 ohms. What is current flowing?
Answer: From the formula:
I= V/R = 9 V / 2 ohms = 4.5 A
Example-2) Calculate the current through a circuit in which the voltage is 15V and resistance is 2Ω?
Answer: From the Formula:
I = V/R = 15/2 = 7.5A
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