What is Direct Current Simple Practical Explanation

What is Direct Current Simple Practical Explanation:

Direct current is generally called as DC, which means the current flow through the conductor in only one direction (the charged particle moves only one direction in the same conductor.). The current does not change its polarity. In a direct current circuit, current is caused by electrons that all lineup and move in one direction. The intensity of the current can vary with time, but the direction of movement remains the same at all times.

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The voltage in a direct-current circuit must be constant, or at least relatively constant, to keep the current flowing in a single direction. Thus, the voltage provided by a flashlight battery remains steady at about 1.5 V.

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The direct current has two terminals; one is positive which denoted in plus symbol (+) and another one is negative which is symbolized by the minus (-). The electron flows from negative terminal to positive terminal, But the conventional current (reference current) flows from positive to negative.

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Direct Current Sources:

  1. Electrochemical Cells
  2. Photovoltaic cells
  3. Batteries
  4. DC generator (Commutator section converts Alternating current to direct current)
  5. Rectifiers (block current reversing in AC, converts AC to DC)
  6. Electromechanical components

Note: Alternating current cannot be stored in any storing device

What are common DC applications?

DC power is widely used in low voltage applications such as charging batteries, automotive applications, aircraft applications and other low voltage, low current applications. All solar panels nowadays produce DC power.

We use batteries in TV remotes, AC remotes, mobile phones, motorbikes starters, cars and in many other types of equipment. If you look close to these batteries, you will find plus (+) and minus (-) signs printed on it.

Direct current has a wide range of advantage over alternating current.

DC current Source:

Electrochemical cell:

An electrochemical cell (EC) is a device which generating capable of generating electrical energy from chemical reactions. The electrochemical cells which generate an electric current are called voltaic cells or galvanic cells and the other ones are called electrolytic cells which are used to drive chemical reactions like electrolysis.

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Example: Small AAA battery.

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Photovoltaic cells:

The solar cell is called as photovoltaic cell. The photovoltaic cell converts light energy into electrical energy. It generates direct current from sun lights.


A battery is a direct current storing device. The battery converts electrical energy to chemical energy during charging time and chemical energy to electrical energy during discharging time.

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DC generator (Direct current generator):

The DC generator converts mechanical energy into electrical energy, Actually, the fundamental developed voltage in the DC generator is AC but the AC is converted into DC with the help of commutator. Hence, We get direct current as output from the DC generator. Also, Such machines are used as the motor as well as the generator.

Example: Take a Railway traction system. The rail starts with Direct current motors and pickups the speed until your desire (drawing current from the source, electrical energy to mechanical energy conversion) and if you want to reduce the speed, then use the same motor as DC generator (as a break), the DC current is fed to the source (mechanical energy to electrical energy).

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We can convert the electric current from an AC source into Direct Current by using an electronic device called rectifier. A rectifier converts Alternating Current (AC) into Direct Current (DC).

Example: Battery charger, UPS

Electromechanical components

Converts mechanical action into electrical action. This method is used in control system for controlling automated valve, mechanical switches, flow meter, etc.

Example: Transducer



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