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DC circuit refers to the closed path in which DC current flows. In these types of circuits the current flows in only one direction and mostly it is used in low-voltage applications.
- An electronic circuit is composed of individual electronic components, such as resistors, capacitors, transistors, diodes, and inductors, connected by conductive wires through which electric current can flow.
- Depending on the type of current flowing through a circuit is divided into two categories DC circuit and AC circuit.
- The circuit that works on DC current is known as the DC circuit and the circuit that works on AC current is known as the AC circuit.
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Key Terms: DC current, Batteries, Resistance, Power, Resistors in series and parallel, Electric circuits, Alternating current
DC Current
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Direct current (DC) is the passage of electric charge in only one direction.
- A good example of DC power is an electrochemical cell.
- Direct current can flow through a conductor, but it can also flow through semiconductors, insulators, or even through a vacuum as in electron or ion beams.
- DC current can be converted from AC current by using a rectifier.
Direct Current
DC Circuit
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A DC circuit is an electrical circuit made up of any combination of constant voltage, constant current, and resistors.
- The circuit voltages and currents are time-independent in this case.
- The circuit voltage or current is not affected by the past value of any circuit voltage or current.
- This means that the equations used for describing a DC circuit do not include any time integrals or derivatives.
DC Circuit
Also Read: DC Generator
DC Circuit Types
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DC circuits are classified into three types: Series DC circuits, Parallel DC circuits, and Series and parallel DC circuits.
Series DC circuits
A series circuit is formed when two or more components are connected end to end. In series DC circuits, resistive components are connected end to end, forming a linear path for current flow.
Consider resistors of resistances R1, R2, and R3 are connected in series, and V1, V2, and V3 be the potential across them respectively.
Series DC circuit
Let V be the potential difference across the circuit, then
V = V1 + V2 + V3
If the current flowing through the combination is I and R be the equivalent resistance, then
IR = IR1 + IR2 + IR3
⇒ R = R1 + R2 + R3
Therefore, the total resistance of the circuit is equal to the sum of individual resistances.
Parallel DC circuits
When many electrical components are connected in parallel, one end of each element is connected to one common point and the other end is connected to another common point. All resistors have one end connected to a common point, while the other ends are connected to another common point (current flows through them).
Consider resistors of resistances R1, R2, and R3 are connected in parallel, and I1, I2, and I3 be the current flowing through them respectively.
Parallel DC circuit
The total current flowing through the circuit is
I = I1 + I2 + I3
If V is the potential difference across the combination is I and R is the equivalent resistance, then
V/R = V/R1 + V/R2 + V/R3
⇒ 1/R = 1/R1 + 1/R2 + 1/R3
Series-Parallel DC circuit
In reality, most electrical circuits are a mix of series and parallel DC circuits. Ohm's Law and principles for parallel and series DC circuits are used to solve these complicated circuits.
Series-parallel DC circuit
In the above DC circuits, R1 and R2 are connected in parallel and both are connected in series with the parallel combination of resistances R3, R4, and R5
The equivalent resistance between A and B is
1/RAB = 1/R1 + 1/R2
The equivalent resistance between B and C is
1/RBC = 1/R3 + 1/R4 + 1/R5
The equivalent resistance between A and C is
R = RAB + RBC
Also Read: Difference between watts and volts
Difference Between AC and DC Circuit
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The following are the differences between AC and DC circuit
| AC Circuits | DC Circuits |
|---|---|
| Current in AC circuits flow in both directions and they reverse periodically. | The direction of the current in DC circuits is unidirectional. |
| The circuit elements in AC circuits are resistors, capacitors, inductors, diodes, etc. | A DC circuit consists mostly of resistive elements, such as a DC battery, a switch, an ammeter, a voltmeter, a load bulb, and connecting leads. |
| The voltage in AC circuits can be stepped-up or stepped down using a transformer. | The voltage in DC circuits can not be stepped-up or stepped down using a transformer. |
| Power loss in AC is more than in DC | Power loss in DC is less than in AC |
Application of DC Circuit
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The applications of DC circuits are
- DC circuits are useful for low and extremely low-voltage applications, such as solar cells and batteries.
- Also, most electronic gadgets require a DC power supply and a DC voltage.
- When utilizing DC devices, it is important to keep the polarity of the DC in mind.
- Even if DC devices have a diode bridge element, it is best to connect the correct polarity.
- DC voltage is commonly used in the automobile industry.
- For example, electric cars use DC voltage.
- These vehicles are powered by batteries.
- In addition, diesel engines in heavy-duty machinery, big vehicles, and machinery commonly use DC voltage systems.
Also Read:
Things to Remember
- The closed path in which DC current flows is called a DC circuit.
- DC is mainly used in low-voltage applications.
- The flow of electric charge in just one direction is referred to as direct current (DC).
- There are three types of DC circuits namely Series DC circuits, Parallel DC circuits, and Series and parallel DC circuits.
- In series DC circuits, the components are connected one after the other.
- In parallel DC circuits, one terminal of all the components is connected to one terminal of the battery, and the second terminal of all the components is connected to the second terminal of the battery.
- Mix grouping of series and parallel circuits is known as a Series-parallel DC circuit.
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Sample Questions
Ques. What are the three types of DC circuits? (2 Marks)
Ans. DC circuits are classified into three types
- Series DC circuits
- Parallel DC circuits
- Series and parallel DC circuits.
Ques. How many switches are in a series DC circuit? (2 Marks)
Ans. A series DC circuit has only one switch. The entire circuit is controlled by a single switch. We cannot regulate each component of the circuit independently.
Ques. What is voltage? (1 Mark)
Ans. It is the energy that drives electric current into a conducting coil from an electrical circuit's power source.
Ques. What is a resistor? (1 Mark)
Ans. It is an electrical device having two ends that are used to restrict or regulate current flow in electrical circuits.
Ques. Why is AC voltage preferred over DC voltage? (3 Marks)
Ans. AC voltage is preferred over DC voltage because transmission of AC voltages results in less energy loss. DC voltages, on the other hand, dissipate a lot of energy during transmission. Because AC voltages result in less energy loss, they are simple to install when transformers are located a long distance away. Furthermore, AC voltage may be stepped up and down as needed. This is an extra benefit.
Ques. What are the advantages of AC over DC? (3 Marks)
Ans. AC offers various advantages over DC. One advantage of AC over DC is that it is less expensive. It is also quite simple to make AC. You can send alternating currents across great distances with minimal energy loss. DC, on the other hand, is quite costly and suffers from energy loss during transmission. In addition, DC is more costly.
Ques. Why is DC stored in batteries? (3 Marks)
Ans. Batteries do not store energy directly in them. Batteries are made to store electrical energy in the form of chemical energy. In this situation, the positive terminal of the AC source is connected to the positive terminal of the battery, and the negative terminal of the AC source is connected to the negative terminal of the battery. When all of this occurs, the current begins to flow. However, there is a polarity change and there is no energy supply. This is due to the negative half cycle canceling out the negative half cycle. If this procedure continues, the battery may be damaged. As a result, AC is not stored in batteries.
Ques. What are the main elements or components of a DC circuit? (2 Marks)
Ans. A DC circuit consists mostly of resistive elements, such as a DC battery, a switch, an ammeter, a voltmeter, a load bulb, and connecting leads.
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