Difference between ac and dc current

Difference between ac and dc current

Let’s go to understand the term, Electric Current.

Simple definition

The follow of the free electron through the conductive materials is called Electric Current.


Travelling of Electrically charged particles through wire when Electrical force applied.


What is the SI unit of current?

The SI unit of Current is Ampere and denoted by ( I ).

and Electric current is measuring by the term (Ampere ) I.


Direction flow

The flow of current direction from the negative terminal to the positive terminal.

one diection flow

applied emf

random electron flow

The unit of charge is the coulomb.

1 Ampere = 6.24 x 1018

Current is the rate of Electron flow.

one coulumb used to be the magnitude of electrical charge in 6.24 x 1018 Electrons.

one amp of current used to be defined by the one coulomb every second.

Formula to find current.

Current(Amp) = charge (coulumb) / Time (second ).

In other words, coulomb is the unit of electrical charge whereas therefore ampere is the unit of electrical current (I).

Type of Electrical Current.

There are basically two types of electrical current.

The first one is Direct Current.

The second one is the Alternating Current.

The Alternating Current.

The alternating current can be seen in the figure.

alternating current



Its flows from the negative ( – ) to positive  ( + ), and positive to negative direction by a certain time period and it represented to sine wave can be seen in the figure.

Application and uses of Alternating current.

Alternating current is widely used in industry and household appliances on the planet of earth.

Some household appliances are Refrigerator, electric iron, heater, etc.

Direct current:

Direct current is can be written as short-form DC.

direct current

Definition of direct current.

The flow of free electrons in only one direction in the conductive materials.

direct current can be found in batteries, Mobile phones, calculators, computers, solar power, and solar cells, etc.



Application and uses of direct current.

direct current is widely used in vehicles to starting the engines, lighting and ignition system, and solar power system.


DC to AC  converter, DC current is converted into AC with the help of inverter to be used in the home base used AC Appliances.

Effect of Electric Current.

Magnetic Effect

When current flows through to the conductor the Magnetic field is growing up around the wire. For e.g: In a magnetic compass is put near the wire the compass needle is deflected or move. That means the magnetic flux is produced around inside or current caring conductor material.

Relay and Loudspeaker are the example of magnetic field produce and energize the relay.

Heating Effect.

Heat is generated when current is passing through the wire, The amount of heat depends on the amount of current and cross-sectional area used in the material.

The possibility of a total amount of heat is produced not depend only on the current, but it is also to be the amount of resistance and the applied voltage of the current-carrying materials.

Example: Hot water heater is the most common example of a heating effect.

How to calculate the electric current?

there are two way to calculate electric current,

  1. Through the multimeter.
  2. Through the ohm law.


The multimeter is one of the easiest ways to calculate the electric current, one probe of multimeter wire is connected to the circuit and another probe of wire is connected to series of the circuit as shown in the figure.

ampere meter


ohm’s law

It is the way to calculate the electric current through that ohm’s law.

First of all, we can understand what is ohm’s law and what is the role of current I that ohm’s law.

ohm’s law says that the current flow in the resistor between two points, it is related to the applied electric force ( voltage ) difference between the two points and it is inversely proportional to the resistance between points. that current and voltage, resistance relation is shown in the equation below:

R= V/I

where i is denoted by the current in ampere, V is denoted by the voltage, and the R is denoted by resistance in the circuit.

In the DC circuit current is directly proportional to the voltage passing inside the resistor and inversely proportional to the resistance in the circuit.

The relationship of ohm’s law states that is written by these Formulas,

R=V/I, I=V/R,  V= I X R.




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