What is current? (Beginners, 2024)

Electric current is one of the most fundamental concepts in electronics. But the question is what is current?

As we know matter has charge particles and voltage forces that particle to flow. The flow of these charged particles creates current. Electric current is measured in amperes (A), which indicates the rate at which charge is flowing. Types of current are AC and DC.

In this article, we’ll break down the basics of electric current, its types, and how it is measured.

Current definition

As we know an atom has electric charges positive (Proton) and negative(electrons), mostly electrons become free and start randomly moving within a conductor.

This random movement of electrons is useless, so voltage is the pushing force that makes electrons move in a specific direction—the movement of electrons due to voltage produces current.

Basically, the current is the flow of charges. The current is defined as,

Current is the rate at which electric charge flows through a conductor or a particular point in a circuit.

If we consider a water tank filled with water and a valve. The pressure of the water is voltage, so if we open the valve the water will start flowing from it so the flow of water from the valve is the current.

So the pressure in this case voltage causes the water (current) to flow.

Let’s take an example of an electronic circuit, considering a circuit with a battery at one end and a bulb (load) at the other. Through a conducting wire, the battery, and bulb two are connected.

The potential difference (voltage) across the battery pushes the electrons to flow from negative to positive and through the load (bulb). These flowing electrons produce current and light up the bulb.

The current flowing from the negative to the battery’s positive terminal is called electronic current. Most of the time conventional current is considered in the literature, which travels from the positive to the negative terminal of the battery.

To learn more about electronic and conventional current, read out article:

Electronic and conventional current for beginners

Remember that an object’s capacity to conduct current is determined by how many charges it can move. Some materials offer better flow charges than others.

As we know, the materials are categorized into three types depending on their current conductivity. These are conductors, insulators, and semiconductors.

Conductors are very good conductors of current, insulators are poor conductors and then there are certain substances known as semiconductors, which sometimes appear to be effective conductors but not other times.

The moving charges are always electrons (negative charge) in the metals (conductors). In gases, these charges are positive and negative ions.

While in semiconductors the current is partly by electrons (negative charge) and partly by a motion of holes (positive charges).

In some literature, the current is also defined as the rate of flow of electrons so it all depends on which material you are working on.

The formula of the Current

Current is the rate of flow of charges, which means how many charges are passed through a given point per unit of time.

So it can written as,

I=Q/t

Here ‘I’ represents the current, ‘Q’ is the amount of charge that passes the point in the wire over some amount of time ‘t’.

Current can also be calculated by Ohm’s law. Ohm’s law states that the magnitude of the current is directly proportional to the applied voltage when the temperature of the conductor is kept constant.

It is represented as,

I ∝ V

And,

V = IR

Where ‘R’ is the constant and is called the resistance of a conductive material. Resistance depends upon the nature, dimension, and physical state of the material.

So the current is equal to,

I= V/R

These are some formulas that can be used to calculate the current in the circuit.

Unit of Current

The SI unit of current is Ampere and it is denoted by ‘A’ or amps. It is one of the SI base units for electric current and it is used in electronic and electrical and other fields.

Ampera is the largest unit of the current, most of the time current is measured in smaller units like mA or milliamps (milli-ampere).

The current will be one ampere when one coulomb of charge flows across the conductor in one second.

1A=1coulomb/1sec

The unit of current can also be defined in terms of Ohm’s law. When a potential difference of 1Volt is applied across the resistor of 1ohm (Ω) will cause 1A current to flow through it.

1A=1volt/1Ω

Current ratings

When you start working with electronic components you will see the term called current ratings.

Current ratings refer to the maximum amount of electric current (measured in amperes, A) that a device, conductor, or component can safely handle without overheating or being damaged.

Exceeding this limit will damage the component or can affect the circuit’s overall performance.

To prevent overloading circuits, ensure proper component selection, and maintain the longevity of electrical systems, understanding the current rating is essential

Types of current

There are various types of current but the two main types of current are direct and alternative current. Let’s see what are they in detail.

1. Direct current (DC)

The direct current is the type of current in which current flows in one direction. In other words, the magnitude of the current remains constant.

Direct current can be created by the circuit of batteries. In the battery, the electrons travel in one direction from the anode (positive) to the cathode (negative) of the battery.

When we plot the graph of direct current with time it is a straight line which means the current is not changing with time and it is constant.

2. Alternative current (AC)

In alternative current, the magnitude and the direction of current changes with time. The flow of electric charges reverses with time.

Let’s see the current-time graph of alternative current.

From the graph, you can see that the current starts from zero then gradually increases and goes to the maximum and again decreases to zero.

After you can see that the current reaches the maximum but in the opposite direction from zero to negative maximum then again to zero.

The graph of alternative current is just like a wave. Alternate current can be changed from a higher voltage level to a lower voltage level, it is typically utilized to power applications.

In our home, the current we use is alternative current.

How to measure current?

One of the most challenging and insightful readings in the field of embedded electronics is reading current.

Different methods can be used to measure current but the most famous and easy way is using a digital multimeter and clamp meter.

1. Digital multimeter

A digital multimeter is an instrument that provides a variety of options to measure basic measurements of electronic circuits. It measures current, voltage, and resistance.

To measure current, it is essential to learn the basics of a multimeter in detail. Most of the multimeter has a rotary switch, and it decides which parameter will be measured.

Follow the following steps for the current measurement.

The first step is to set that switch to the current function.
Connect the black (negative) and red (positive) terminals of the test leads to “COM” and “A,” respectively.
For current measurement, you have to connect the multimeter in the series to the circuit so we have to break the circuit.
Now Connect the red wire to the load side and the black lead to the power supply’s negative side.
Note the current reading from the multimeter display.

In this way, the multimeter will measure the current flowing in the circuit.

2. Clamp meter

For AC currents or certain DC applications, a clamp meter can be used without breaking the circuit. The clamp wraps around a single conductor, and the meter displays the current passing through it.

Follow these steps:

Switch the clamp meter on by rotating its dial to the AC or DC measurement mode.
Open the clamp jaws by pressing the lever. This will allow you to position the clamp around the conductor.
Place the clamp meter around a single conductor wire.
Release the clamp lever to close the jaws securely around the wire.
The current reading will be displayed on the meter display.

This is how you can measure current without breaking a circuit by using a clamp meter.

Conclusion

Current is the rate of flow charges. These charges can be positive or negative depending on the material.

The conductors have a lot of electrons that move freely in the atom when the potential difference is applied it will push the electronics to move in one direction and these flow charges are called current.

Mathematically current can be calculated through Ohm’s law and will also be calculated in terms of charge per unit time. The unit of current is Ampera (A).

Direct and alternative current are the main types of current, there are also some other types such as steady current, varying current, and instantaneous current.

To measure the current in the circuit, a digital multimeter is an easy and convenient option. The clamp meter can also be used to measure AC.

This is all about current, I’m hoping it will be useful.

Thank you…