Difference Between AC And DC

What is an Alternating Current (AC)?

The electric current that periodically reverses its direction is called alternating current (AC). It flows first in one direction and then in the other many times every second, and this change happens over a given timeframe, usually called a cycle.

AC is the type of electricity coming out of power stations and used in domestic, commercial, and industrial settings. It can run lights, fans, televisions, and refrigerators. The primary reason we use AC voltages in houses is that they can be transmitted over long distances through wires with minimal energy loss.

Types of AC

Mainly, AC is of two types:

Sinusoidal AC:

• This is the commonest type of ac.
• The current varies smoothly in the shape of a sine wave.
• It is found in homes, schools, offices, and factories. E.g. Electricity from grid supply.

Non-sinusoidal AC:

• This waveform does not possess a smooth sine waveform.
• It includes square waves, triangular waves, and other waveforms.
• Utilised for some special devices such as inverters, digital clocks, and also in signal circuits.

What is Direct Current (DC)?

Direct current, more commonly known as DC, is a steady current flow that travels in one direction and does not change its direction as in AC. Generally, the elements produce DC with constant and continuous flow, making it preferable for most miniature electronic circuits. The batteries, solar cells, and power banks are sources of this direct current.

For example, when you put a battery in the remote control or torch, the output will be direct current. But most generally used devices, such as mobile phones, laptops, and LED lights, run on DC even if they are charged from a wall socket using AC. The device connected to the charging socket is actually converting AC power into DC power.

Types of DC

There are mainly four types of DC current, which are listed below:

Unipolar Direct Current

• The voltage stays on one side of the zero line (either always positive or always negative).
• It is the more common type of DC. Example: Output from battery.

Bipolar Direct Current

• The voltage may be either positive or negative, while it always travels in one direction-current.
• Generally applied in processing signals as well as control systems. For example: power supplies in circuits.

Low Voltage DC

• The lowest voltage of all is less than 120V.
• They are generally fed to small electronic devices, housing (solar-powered), and vehicles. Example: The common 5V or 12V from USB chargers or batteries in cars.

High-Voltage DC

• DC voltage higher than 120V, generally in kilovolts (kV).
• They are beneficial in long-distance transport of electricity, and they can transmit such losses. For example, power lines using HVDC for city-to-city supply.

AC and DC Current Examples

Examples of AC (Alternating Current)

• Electricity supply at home, school, and offices.
• Power in factories and industries.
• Current in transmission lines and power stations.
• Household appliances like fans, refrigerators, washing machines.

Examples of DC (Direct Current)

• Current from batteries (torch, mobile, car battery).
• Current from solar cells and fuel cells.
• Current in laptops, smartphones, and other electronic gadgets.
• Current used in electroplating and electrolysis.

Difference Between AC and DC Current

The major Difference between AC and DC in physics is given in the table below:

Related Topics,

• AC Generator
• Reactance and Impedance
• LCR Circuit
• RMS Value Alternating Current

How to convert AC current to Direct current?

AC is changed into DC by a device called a rectifier. A rectifier allows electric current to flow in only one direction, meaning that it blocks the reverse flow of AC and makes it a one-way current like DC. However, the current after rectification is not smooth; it still possesses small ups and downs called ripples. A filter (generally, a capacitor) is applied to smooth this current. In certain cases, a voltage regulator is also used to stabilise the voltage. These are the phases through which the mobile chargers and adapters convert AC from the wall to DC for your devices.

Applications of AC (Alternating Current)

• Used in homes, schools, and offices for lights, fans, refrigerators, TVs, etc.
• Powers industries and factories with heavy machines.
• Used in long-distance power transmission because it can be easily stepped up or down with transformers.
• Runs AC motors in appliances like washing machines, air conditioners, and pumps.

Applications of DC (Direct Current)

• Used in batteries (torch, mobile phones, laptops, cars).
• Powers electronic devices like radios, TVs, and computers (internally work on DC).
• Used in electroplating, electrolysis, and welding.
• Essential for low-voltage applications like LED lights, solar cells, and electric vehicles.

Also, check-

• NCERT Exemplar Class 11th Physics Solutions
• NCERT Exemplar Class 12th Physics Solutions
• NCERT Exemplar Solutions for All Subjects