What is an Alternating Current?
Based on the direction of current flowing through the circuit, it is differentiated in two types. One is Alternating current and another is Direct current. When an electric current reverses its direction periodically while flowing through an electric circuit is called Alternating Current (AC). On the other hand, when current flows in only one direction is known as Direct current (DC).
The major advantage of alternating current is that AC voltages can be easily transformed from higher to lower voltage levels and vice-versa. Due to this virtue, high voltage power from power stations can be reduced to a safer voltage for domestic use. Only Alternating current is compatible with capacitors and inductors. By using them within the Alternating current circuits, the flow of electricity can be turned. This property helps tune the radio stations. Because of these reasons, AC electricity is most preferred for home appliances.
Power Consumed in an AC Circuit
An electric circuit produces power which is given by the expression, P= I V.
Where, I – the current flowing through the circuit and
V- Voltage across it.
AC circuits always offer reactance, therefore there are two components of power, a power component because of the magnetic field and another because of the electric field. The average power absorbed by the circuit becomes the sum of power stored and returned through a complete one cycle. Thus, the average power consumed by the circuit will be the instantaneous power within one cycle.
Power Factor
The power factor of an alternating current is defined as the ratio of the true power flowing through the circuit to the apparent power present in the circuit.
It is usually in the interval of -1 to 1 and is dimensionless.
Power Factor = \[\frac{ \text {True power}}{\text{Apparent power}}\]
Also, cosΦ = \[\frac{R}{Z}\]
R- resistance in the circuit
Z- impedance of the circuit.
Definition of Power in AC Circuit
The rate of doing work or the amount of energy transferred by a circuit per unit time is known as power in AC circuits. It is used to calculate the total power required to supply a load. Power factor: In an AC circuit, the power factor (PF) is defined as the ratio of real power (P) to apparent power (S). The PF can be expressed in percent or decimal form.
The Importance of Power in an AC Circuit
The power in an AC circuit is very important as it determines the amount of current that flows through the circuit and hence, the size of the wire required. The voltage and current waveforms are also affected by the power factor. A low PF means that a lot of energy is being wasted in the form of heat due to poor utilization of electricity. This can cause overheating and failure of electrical equipment.
The Importance of the Power Factor
The power factor is very important as it determines the amount of current that flows through the circuit and hence, the size of the wire required. The voltage and current waveforms are also affected by this factor. A low PF means that a lot of energy is being wasted in the form of heat due to poor utilization of electricity which can cause overheating and failure of electrical equipment.
Here are Some Tips to Study the Power in AC Circuit
Knowing how to solve simple AC circuit problems helps you learn more about PF and its applications in real-life situations. Some examples include finding the reactive watts, total watts, current, and voltage for a given power factor. These examples can help you learn more about PF and its applications in real-life situations. Here are some tips to study the Power Factor:
Know the basics- It is important to know the basics of an AC circuit before studying the power factor. So that, you can easily understand the importance and applications of the power factor. Solve simple problems- Knowing how to solve simple AC circuit problems helps you learn more about PF and its applications in real-life situations. Some examples include finding reactive watts, total watts current, or voltage for a given power factor. Learn from textbooks - Textbooks contain detailed information on formulas along with solved examples.
Practice more problems- Practicing a lot of examples is one of the most effective ways to learn and understand the concept of the power factor which will help you to use the power factor in real-life problems.
Understanding and applying PF concepts is an important part of learning more about electrical equipment and devices that implement it.
Studying examples from textbooks along with practicing lots of problems helps one learn quickly as well as understand PF better which ensures correct usage in real-life situations.
Appear for mock tests- Mock tests help you understand where you stand with the concept of power factor. Last but not least, appearing for mock tests gives one an idea about how much they have learned about power factors and what all they need to focus on.
Learn the rules- It is important to learn the rules of the power factor before solving any problem.
Fun Facts
Ohm’s law for the RMS value of an alternating current is calculated by dividing the RMS voltage by the impedance.
The average power delivered to an LCR circuit varies with the phase angle.
FAQs on Power in AC Circuit
1. How is an Alternating current produced?
Various sources of electricity such as electromechanical generators, produce current.
The current is produced with voltages such that it alternates in polarity, reversing between positive and negative over time.
Many times, an alternator is used to generate alternating current.
When a magnetic field generates in an alternator, a loop of wire is rapidly inserted to produce an electric current.
As the wire starts spinning, it attains polarity, and consequently voltage and current get induced. The generated current can change the direction.
As the current reverses its direction, the voltage too changes the direction accordingly.
If an AC circuit is connected to an oscilloscope and the behavior is plotted against the time, then several waveforms (sine, triangle and square) are observed. Most buildings are wired with an oscillating voltage in the sine waveform
2. What are the applications of an Alternating current?
Generation and transportation of alternating current over a long distance is comparatively easy, that is why Alternating current is mostly used in mains-wired buildings (offices, residential complexes).
At high voltages less energy is utilized in power transmission. At high voltages, lower currents are produced resulting in less heat in transmission lines as they have comparatively less resistance.
Alternating currents can be easily converted to high voltage from low voltage and vice-versa by using transformers.
Alternating current is of great use in electric motors. These motors are used in home appliances such as refrigerators, washing machines, air conditioners.
3. How much does it take to complete the whole topic to prepare for exams?
Learning the concept is not easy but it can be done in a small time frame. The important thing is to know where you stand with your learning and then keep practicing more problems until you have mastered the topic before appearing for any exam.
4. How much should I practice?
Practicing a lot of examples is one of the most effective ways to learn and understand PF better which ensures correct usage in real-life situations. You need to solve at least 20-30 questions per day, this helps you retain what all you are taking up!
5. What do I need help with?
Understanding power factor concepts along with their applications in real-life situations requires continuous study over several days rather than cramming them in one day.
6. What are the benefits of appearing for mock tests?
Mock tests help you understand where you stand with the concept of power factor. Last but not least, appearing for mock tests gives one an idea about how much they have learned about power factors and what all they need to focus on. As a result, it is important to appear for such tests if you want to score better in your exams!
7. What should I expect from this topic in exams?
You will be asked to solve simple AC circuit problems, find reactive watts, total watts, or voltage for a given power factor. These examples can help you learn more about PF and its applications in real-life situations.
A good understanding of this topic ensures that one uses electrical equipment efficiently without causing damage due to excessive current flow! - Keep practicing questions so as to ensure your success at all times! It becomes easy when concepts get clarified with sufficient practice over several days rather than cramming.
8. What other topics can I expect from the same chapter?
If you are preparing for an engineering entrance exam, then this topic will be part of your syllabus apart from being a part of the physics paper in class 12th board examinations. Solving simple AC circuit problems helps you learn more about PF and its applications in real-life situations. Some examples include finding reactive watts, total watts current or voltage for a given power factor. It becomes easy when concepts get clarified with sufficient practice over several days rather than cramming it.
