Alternating current and direct current

Electricity comes in two forms: alternating current (AC) and direct current (DC) . Both are essential to allow our electronics to function, but do you know the difference between the two and what does each apply to? Read on to get all the information.

Alternating current
DefinitionAlternating current (AC) power is the standard electricity coming out of electrical outlets and is defined as a flow of charge that exhibits a periodic change of direction.Direct current (DC) energy, as can be deduced from the name, is a linear electric current: it moves in a straight line.
Causes of electron flowRotating a coil in a uniform magnetic field or rotating a uniform magnetic field within a stationary coilConstant magnetic field through the wire.
Frequency50 of 60 herciosZero
Direction of electron flowBidirectionalUnidirectional
Power factorIt is between 0 and 1Always 1
PolarityIt has polarity (+, -)It has no polarity
Obtained fromAlternatorsGenerators, battery, solar cell, etc.
Type of loadIts load is resistive, inductive or capacitive.Its load is usually resistive in nature.
Graphic representationIt is represented by irregular waves such as triangular wave, square wave, sine wave.It is represented by a straight line.
TransmissionIt can be transmitted over a long distance with some loss.It can be transmitted over very long distances with negligible losses.
ConvertibleEasily converts to direct currentEasily converts to alternating current
SubstationLittle substation is required for generation and transmissionMore substations are required for generation and transmission
Passive parameterImpedanceEndurance
DangerousnessDangerousVery dangerous
UseFactories, Industries and for domestic use.Electroplating, electrolysis, electronic equipment, etc.

What is AC

Power alternating current (AC) is standard electricity coming out of the outlets and is defined as a charge flow which exhibits a periodic change of direction. This changes between positive and negative due to the electrons; Electric currents come from the flow of these electrons, which can move in a positive (up) or negative (down) direction. This is known as a sinusoidal AC wave , and it occurs when alternators in power plants generate AC power.

Alternators create AC power by rotating a loop of wire within a magnetic field . Alternating current waves are formed when the wire moves into areas of different magnetic polarity; for example, the current changes direction when the wire rotates from one of the poles of the magnetic field to the other. This wave motion means that alternating current can travel further than direct current , a huge advantage when it comes to supplying power to consumers through electrical outlets.

What is direct current

Direct current (DC) energy , as can be deduced from the name, is a linear electric current: it moves in a straight line. This can come from multiple sources, including batteries, solar cells, fuel cells, and some modified alternators . DC power can also be “made” from AC power using a rectifier that converts AC to DC.

DC power is much more consistent in terms of voltage supply, which means that most electronic devices rely on it and use DC power sources such as batteries. Electronic devices can also convert AC power from outlets to DC power by using a rectifier, often built into a device’s power supply. A transformer will also be used to raise or lower the voltage to an appropriate level for the device in question.

However, not all electrical devices use direct current. Many devices, especially household appliances, such as lamps, washing machines, and refrigerators, use AC power, which is delivered directly from the electrical network through electrical outlets.

When the two types of energy are used

Although many of today’s electronic and electrical devices prefer DC power due to its smooth flow and even voltage, we couldn’t do without AC. Both types of power are essential; one is not better than the other .

In fact, CA dominates the electricity market; All electrical outlets carry power into buildings in the form of AC, even though the current may need to be immediately converted to DC power. This is because DC is not able to travel the same long distances from power plants to buildings using AC. It is also much easier to generate AC than DC due to the way the generators rotate, and the system is generally cheaper to operate; With AC, power can be transported over miles and miles of power lines and pylons with ease.

DC comes into play primarily where a device needs to store energy in batteries for future use . Smartphones, laptops, portable generators, flashlights, outdoor CCTV camera systems … you name it, anything that runs on batteries relies on storing DC energy. When batteries are charged from the mains, AC is converted to DC by a rectifier and stored in the battery .

However, this is not the only charging method used. If you’ve ever charged your phone with a power bank, for example, you’re using a DC power source instead of an AC one. In these situations, the DC-DC power supplies may need to change the output voltage (in this case, the power bank) for the use of the device (in this case, the phone).

Key differences between alternating current and direct current

  • The current that changes direction in a regular time interval of this type of current is called alternating current. Direct current is unidirectional or flows only in one direction.
  • Charges in alternating current flow by rotating a coil in the magnetic field or by rotating a magnetic field within a stationary coil. In direct current, the charges flow keeping the magnetism constant along the cable.
  • The frequency of alternating current is 50 to 60 hertz depends on the country standard, while the frequency of direct current always remains zero.
  • The power factor of alternating current is between zero and one, while the power factor of direct current always remains the same.
  • Alternator current is generated by the alternator. Direct current is generated by the generator, battery, and cells.
  • The load of the alternating current is capacitive, inductive or resistive. The direct current load is always resistive in nature.
  • Alternating current can be graphically represented through different irregular waveforms such as triangle wave, square wave, periodic wave, sawtooth wave, sine wave, etc. Direct current is graphically represented by the straight line.
  • Alternating current transmits long distances with some losses, while direct current transmits very long distances with negligible losses.
  • The alternating current is converted into direct current with the help of a rectifier, while the direct current is converted into alternating current with the help of the inverter.
  • Few substations require the generation and transmission of alternating current. Additional substations are required for direct current transmission.
  • Alternating current is used in industries, factories and for the home. Direct current is mainly used in electronic equipment, hybrid vehicles, electroplating, electrolysis, etc.

Point to remember

Direct current is more dangerous than alternating current . In the second, the magnitude of the current becomes high and low at regular intervals of time and in direct current, the magnitude remains the same. When the human body receives a shock, alternating current enters and leaves the body in a regular interval of time, while direct current afflicts the body continuously.

Frequently asked questions about the difference between AC and DC

Why can’t AC be stored in batteries instead of DC?

It is important to understand that batteries do not store energy directly in them. They store electrical energy in the form of chemical energy. The positive terminal of an AC source is connected to the positive terminal of the battery and the negative terminal of an AC source is connected to the negative terminal of the battery. The current begins to flow, but the AC changes its polarity and there is no real power supply. This is because the positive half cycle cancels the negative half cycle. If this process continues, it may damage the battery. Therefore, AC is not stored in batteries.

What are the advantages of AC over DC?

The following are the advantages of alternating current over direct current:

  • AC is less expensive and easier to generate than DC.
  • The distance covered by AC is greater than that of DC.
  • Power loss during AC transmission is less compared to DC.

Why is the use of AC voltage preferred over DC voltage?

There are two reasons why the use of AC voltage is preferred over DC voltage:

  • The energy loss during transmission in alternating voltage is less compared to direct voltage and this facilitates its installation when the transformers are remote.
  • AC voltage has the advantage of increasing and decreasing according to the requirement.

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