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JEE Exam » JEE Study Material » Physics » Alternating Currents

Alternating Currents

Understand alternating currents study material, its applications, converting alternating current to direct current, SI unit, the relation between direct current and alternating current, and much more

Introduction

Alternating current is a type of current whose direction changes periodically through a load. A complete cycle of an alternating current comprises a negative cycle and a positive cycle.

When graphically represented, a positive cycle begins from the axis, reaches the maximum positive value upwards and returns to zero (axis). Similarly, a negative cycle starts from the axis, reaches the maximum negative value downwards and returns to zero (axis). Such graphical representation is known as a sinusoidal waveform.

Current

Current can be defined as the rate of flow of charge. The person behind this incredible invention is Benjamin Franklin.

Here, I = q/t = total charge/time, and

Iavg = Δq/Δt

Iinstantaneous = dq/dt

One of the common examples of current electricity is lightning which travels from the sky to the Earth. Further, current electricity is divided into two major types: the direct current denoted by DC, and the alternating current is known as AC. 

What is an Alternating Current?

Alternating current or AC can be defined as the electric current where the direction of the current electricity keeps on changing. AC changes its polarity and magnitude at regular intervals. This occurs due to regular fluctuation in the voltage leading to periodic back and forth for the current. Alternating current is used in household equipment.

The direct current flows in a defined direction, whereas the alternating current increases to a maximum and then returns to zero after a certain point. Later, the particles change their direction and again reach their maximum point. The same cycle keeps on repeating again and again.

Generation of Alternating Current 

The device used to generate or produce the alternating current is called an alternator. However, several other methods are used as well. One of the most common is producing alternating current using a single-coil AC generator with a single wire loop and two-pole magnets rectangular. 

Applications of Alternating Current 

Alternating current is commonly used in electrical household appliances. A radio signal, audio signal, etc., are typical examples of alternating current. Since the alternating current is a safer option for transferring current to long distances without losing electric power, it is preferred as compared to direct current, which is not suitable for travelling a long distance as it loses electric power.

Relation between Alternating Current and Direct Current 

Alternating current and direct current are related to each other.

Alternating current can be defined as a current which keeps on changing its polarity and magnitude at a constant period. Whereas direct current is a type of current electricity whose magnitude and polarity remain constant. It can be defined by the regular flow of electrons that flow from the region of the higher potential to the lower potential. 

The significant differences between the direct current and alternating current in a tabular form for better understanding. Let’s have a look- 

Alternating Current (AC) 

Direct Current (DC)

Safer for transferring long distances without losing electric power. 

Not suitable for long distances as it loses electric power.

The magnets rotating around are responsible for the change in the flow of electric current.

Since the magnetism is steady, there’s no change in the direction of the flow of electric current. 

The frequency of the alternating current is dependent on the country. However, the frequency remains around 50 Hz to 60 Hz in general.

Direct current has absolutely no frequency.

The current changes its flow and direction to the backward at regular intervals.

There is no change in the flow of the direction. 

The electrons present in alternating current keep changing their directions from backwards to forward. 

In direct current, the electrons only move in the forward direction. 

Conclusion 

An alternating current is a type of electric current that continuously changes according to its frequency. It is used in household appliances and for long-range transfer as the power loss in these currents is significantly less. Then we compared AC current with DC current and got to know that DC current has some flaws covered by AC current.

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Frequently asked questions

Get answers to the most common queries related to the IIT JEE Examination Preparation.

What is the average value of alternating current?

Ans: The average value is the average of all the instantaneous values of an alternating quantity, s...Read full

What is the frequency of alternating current?

Ans: The frequency of alternating current remains around 50 Hz to 60 Hz.

Who discovered alternating current?

Ans: Benjamin Franklin discovered alternating current.

Write the SI unit of the alternating current.

Ans: The SI unit of the alternating current is Amperes, denoted by A 

Give examples of alternating current and direct current.

Ans: The following are examples of alternating current and direct current: ...Read full

What is the key difference between alternating and direct current?

Ans: Out of direct current and alternating current, alternating current is a safer option for transferring long dist...Read full