Electricity & Megnetism

# Difference between ac and dc current in tabular form

## What is the difference between ac and dc current?

Alternating current (AC) and direct current (DC) are two types of current in electricity. The basic difference between ac and dc current is that AC current reverses its direction while flowing in a circuit, while DC current does not change its direction. The alternating current generates frequency while direct current has zero frequency.

Now!

Content

• Introduction of AC and DC current
• Definitions of ac current and dc current
• Advantages of Ac over DC current
• Comparison chart
• Applications of dc and ac currents
• Conclusion

Introduction:

### AC vs DC

Direct current (DC) which is produced by a voltage source whose terminals have fixed polarity. Hence, they provide a current whose direction flow does not change with time. However, this direct current may be steady. The main point is that its direction of flow remains the same i.e, from the positive terminal of the voltage source to its negative terminal.

Some examples of voltage sources are:

1. Cell
2. Battery
3. DC generators

Alternating current (a.c) is produced by a voltage source whose terminal polarity keeps alternating with time. What was the positive terminal at one instant becomes negative terminal some time later becomes positive terminal at some other instant?

As a result of constantly reversing the polarity of the voltage source, the direction of current flow in the circuit also keeps reversing. In addition to reversing to reversing its direction, current keeps changing in value with time from zero to maximum in one direction and back to zero and then again back to zero. It is obvious that an alternating voltage source will cause an alternating current.

It may be noted in passing that ‘a.c’ electricity is not better than ‘d.c.’ electricity as some people feel. Alternating voltages and currents have their own fields of application which d.c does not have and vice versa.Any way.it is important to keep in mind that a.c does not replace d.c, A.C is commonly used in electronic circuits most of which are, however, controlled by d.c voltages.

The most common source of alternating voltage is the alternator or a.c generator.

## Difference between AC and DC current in tabular form

 Alternating Current (A.C) Direct Current (D.C) Definition Alternating current is the type of current which changes its direction after 1800. Direct current is the type of current which does not change its direction periodicity. It remains constant. Amount of energy which can be carried A.C current travel safely at a long distance without losing much energy. D.C current does not travel safely over a long distance because D.C current loss much energy as compared to A.C. Frequency The frequency of A.C current is not zero. The frequency of D.C current remains zero. Magnitude The magnitude of alternating current varies with time. The magnitude of D.C current does not vary with time. Sources A.C current is produced mainly by Generators. D.C current is produced from battery or cell etc. Power factor In A.C current power factor always lies between  0 to 1. In D.C current power factor always remains 1. Types of Waveforms Waveforms of A.C current are a sinusoidal, triangular, square, quasi-square wave. Waveforms of DC current are pulsating and pure. Passive Parameters Impedence Resistance only Applications It is used in homes, industries etc It is used in refrigerators, TV etc

Related questions and their answers of AC current and DC current:

#### Q1: Which is more dangerous current.AC OR DC?

Ans: Alternating current (A.C) is more dangerous than direct current (D.C) because the high voltage is associated with A.C.

DC current and AC current have different effects on the human body, both are dangerous above certain voltage level.

#### Q2: Which current is in battery AC or DC?

Ans: The current in the battery is DC current.

#### Q3: Why do we use AC supply in our homes?

Ans: We use AC supply in our homes because we can change A.C easily with the transformer. High voltage suffers very less loss of energy in long transmission channels or lines, and the voltage can be reduced for safe use at home by using the step-down transformer.

Mathematical prove:

The power loss in the wire is given by:

L = I2R

Where L is the power lost to heat, I is the current and R is the resistance. The power transmitted is given by the relation:

P = VI

In this relation P is the power, V is the voltage.

So if you increase voltage (V) and current (I) small, In this way you can transmit the same power by reducing the power loss. So high voltage gives the best performance. This is the reason we use A.C instead of D.C in our homes.

Note:

High voltage can also be transmitted by DC also, but it is difficult to reduce the voltage for safely use at homes.

In these days advanced DC converters are being used to reduce DC voltage.

#### Q4: Why is AC considered more efficient than DC?

Ans: Because AC current can be converted easily to DC, and the power losses in AC over long distance is less than DC.

#### Q5: Why Can’t AC be stored in batteries?

Ans: AC can’t be stored in batteries, because when you charge your battery with AC source, your battery will not charge.

Point to remember:

AC is an Alternating in nature while DC is constant in nature. During the positive half cycle of AC, the battery gets charged, while during the negative half cycle of AC the battery will discharge. In this way, the battery will not charge even 0.00000001 %.

#### Q6: What are the advantages of AC current?

Ans :

• Distribution, generation, and transmission with AC is simpler than DC.
•  AC supply can be stepped up and down easily.

#### Q7: What are the advantages of DC current?

• Battery cell provides DC supply. There is no any battery cell providing AC supply.
•  Almost all electronic appliances operate on DC.

#### Q8: Which current invented first DC or AC?

Ans: DC current invented much before than AC.

#### Q9: How can we convert AC current into DC?

Ans: We can convert AC current into DC current by using Rectifier circuit followed by a filter.

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