Lowpitch notes such as those produced by a tuba or bassoon consist of air molecule vibrations that are relatively slow low frequency. An ac generator equipped with a device called a commutator can produce direct current. For the case of the alternating current passing through an inductor, the same basic principles are used, but as the waveform is repetitive, we tend to look at the way the inductor responds in a slightly different way as it is more convenient. Problem 1 an alternating current i is given by i 141. A current which flows first in one direction in a circuit, called the positive direction, then in the reverse direction or negative direction is called alternating current. What is the direction of the magnetic field around a vertical conductor when a the current flows upward and b the current flows downward. The voltage and the current are out of phase by 90 o. Class 12 physics revision notes for chapter 7 alternating. Notes on alternating current class 12 page 01 alternating current a. Rms values since voltage and current are always changing we need some way of averaging out their effect. Alternating current vs direct current as useful and as easy to understand as dc is, it is not the only kind of electricity in use.
In this video tutorial, we will understand the basic properties of alternating current ac and cover topics such as ac generator, current through ac generator, ac circuits, power factor, wattless current, and transformers. Get cbse class 12th physics key notes on alternating current. Alternating current, ac and direct current, dc both have their advantages and disadvantages, but this means that there is a choice to select the best option for any given use or application. As the name implies, it flows first in one direction and then the other. This conversion of ac into dc is accomplished through the use of a commutator. Use of a device called a rectifier that converts ac to dc. Alternating current class 12 notes class 12 physics chapter 7 alternating current notes pdf download alternating current ac is the current generated by the vast majority of power plants and used by most power distribution systems, as it is cheaper to generate and has fewer energy losses than direct current when transmitting electricity over long distances. Dec 24, 2019 candidates who are pursuing in class 12 are advised to revise the notes from this post. Certain sources of electricity most notably, rotary electromechanical generators naturally produce voltages alternating in polarity, reversing positive and negative over time. Ac circuits basics, impedance, resonant frequency, rl rc rlc lc circuit explained, physics problems. The direction of the lines of force is given by the law of the screwdriver. Alternating current class 12 notes physics mycbseguide. By its very nature, an alternating waveform is changing all of the time.
Alternating series test we have the following test for such alternating series. The mean value of the ac is defined as equivalent steady current which when passed through a circuit would send the same amount of charge in the same time as is done by the alternating current in the same circuit in the same time. Cbse quick revision note for class12 physics, chemistry, maths, biology and other subject are very helpful to revise the whole syllabus during exam days. These notes are continuation of cbse class 12th physics notes. Mar 05, 2019 class 12 physics notes chapter 7 alternating current.
Candidates who are pursuing in class 12 are advised to revise the notes from this post. Alternating current ac introduction flight mechanic. May 06, 2020 test c alternating current ac assignment class 12 notes edurev is made by best teachers of class 12. Figure 1 shows the plot of alternating voltage and alternating current as a function of time in a circuit that has only a resistor and a source of alternating current an ac generator. Cbse ncert notes class 12 physics alternating current. Download revision notes for alternating current class 12 notes and score high in exams. In this current, the charged particles move from zero to maximum value in a direction and fall to zero and goes for another cycle in the opposite.
In this manner, as more turns are added to the coil, the same current produces larger and larger magnetic. Example 1 test the following series for convergence x1 n1 1n 1 n i we have b n 1 n. Why, alternating current and direct current, of course. Electric charge in alternating current ac, on the other hand, changes direction. It can be represented as, the currents and voltages in a.
The graph above shows the current waveform varying as a sine wave, with the current first moving in one direction and then the other. Electric charge in alternating current ac, on the other hand, changes direction periodically. In electrical circuits energy is dissipated only if a portion of the voltage is in phase with the current. Chapter 12 alternatingcurrent circuits mit opencourseware. But the voltage phasor, 10, is perpendicular to that of the current. Circuit analysis of ac resistive circuits alternating. As we saw with work, energy changed only when a portion of the force was in the direction of the displacement.
An alternating voltage or current is one whose magnitude changes with time and direction reverse periodically. A transformer consists of two electrically isolated coils and operates on faradays principal of mutual induction, in which an emf is induced. Alternating current in this video tutorial, we will understand the basic properties of alternating current ac and cover topics such as ac. Class 12 physics ac notes notes on alternating current.
The phasor diagram representing equation 16 is shown in figure 23. Apr 26, 2020 notes alternating current theory notes edurev is made by best teachers of. Read all the important points and chapterwise notes on aipmt. Powerpoint slide on alternating current compiled by akhilesh kumar. Notes for alternating current circuit chapter of class 12 physics. Alternating current ac electrical systems are found on most multiengine, high performance turbine powered aircraft and transport category aircraft. Introduction to basic notions on electric power 5 electric current conductor lines of force fig. Introduction to alternating current ac learn electronics. The lefthand rule for a conductor is used for what purpose q9. Download cbse class 12th revision notes for chapter 7 alternating current in pdf format for free. V l i m x l, v c i m x c, v r i m r and v v m resistor v r and i are in phase. Ac circuits basics, impedance, resonant frequency, rl rc rlc lc circuit explained, physics problems duration.
Basically, what is alternating in alternating current is the polarity of the voltage source, which causes the current to flow in one direction, and then reverse, and flow in the opposite direction. For simplicity, we sill assume that phase is 0 for the rest of this tutorial. These video classes have been designed to suit the curriculum of. When placed in the vicinity of a currentcarrying conductor, the needle of a compass becomes aligned at what angle to the conductor.
The current in the circuit is impeded by the back emf of the inductor coil. Thats why the main difference you will see between dc and ac circuit diagrams, is that in the ac circuit diagrams, there will be no indication of. C is the current that changes in magnitude direction continuously with respect to time. This document contains detailed info on fundamentals, concept and explanation of various terms and definitions required to perfect knowledge of alternating current page 1 of 1 notesgen is the no. With the help of notes, candidates can plan their strategy for particular weaker section of the subject and study hard. Dec 08, 2016 the unit of angular frequency is radsec. Rather than oscillating back and forth, dc provides a constant voltage or current. The generation of sinusoidal ac voltage can also be explained using. For this we have included pdf notes of each chapter still updating. Figure 1 current and voltage from an ac source through a simple resistor. I we see from the graph that because the values of b n are decreasing, the. These notes are aligned with our channels video lectures.
Alternating current grade 12 physics notes khullakitab. Electromagnetic induction and alternating current revision notes. Basic concepts of alternating current ced engineering. Either as a voltage switching polarity or as a current switching direction back and forth, this kind of electricity is known as alternating current ac. Resistor, inductor and capacitor all are in series.
In fact, the i or rms current is the equivalent dc current that would produce the same average power loss as the alternating current. Class 12 physics notes chapter 7 alternating current. These are the alternating current class 12 notes prepared by team of expert teachers. Lecture notes all ac circuit lectures feeg1004 studocu. Ac is the same type of electricity used in industry and to power our homes. So, go ahead and check the important notes for class 12 physics alternating currents. Then to summarise this transformer basics tutorial. However, it is possible to convert the alternating current that is induced into the armature into a form of direct current. Alternating current, ac and direct current, dc are two forms of electric current that are used each with its own advantages. In particular, if a coil rotates in the presence of a magnetic field, the induced emf varies sinusoidally with time and leads to an alternating current ac, and provides a source of ac. Direct current dc is used on systems that must be compatible with battery. Alternating current, ac is generally used for power distribution, which is why the mains sockets in our homes and at work provide an alternating current to.
Alternating current, ac is different to direct current. Kindly note that some of these notes are not written by us and they are borrowed from student community. Test c alternating current ac assignment class 12 notes. It is the current or voltage that in the circuit at any instant. Since the current is common to all three components it is used as the horizontal reference when constructing a voltage.
Most students of electricity begin their study with what is known as direct current dc, which is. Ohms law yields v l ix l, where v l is the rms voltage across the inductor and i is the rms in the inductor resistorinductorcapacitor circuit. Ac circuits composed of resistors can be analyzed using ohms law and kirchhoffs law just as we did with dc circuits. Sep 20, 2016 may 06, 2020 test c alternating current ac assignment class 12 notes edurev is made by best teachers of class 12. Both ac and dc describe types of current flow in a circuit. These video classes have been designed to suit the curriculum of cbse class 12 students. Care must be taken that correct formulas are used for peak voltages and currents, average voltages and currents, rms voltages and currents.
This document is highly rated by class 12 students and has been viewed 542 times. Students will learn strong basics of electrical engineering and practical. The revision notes covers all important formulas and concepts given in the chapter. In direct current dc, the electric charge current only flows in one direction. Direct current is a bit easier to understand than alternating current. Basic concepts of alternating current cedengineering. The effective resistance is called the inductive reactance x l defined by x l 2. Number of times this current changes its direction in one second can be defined as the frequency of the alternating current. Jan 09, 2018 24 videos play all alternating current tutorials point india ltd. This document is highly rated by students and has been viewed 297 times. A transformer changes the voltage level or current level on its input winding to another value on its output winding using a magnetic field. Note that your fingers point in the direction that the north pole of the compass points when it is placed in the magnetic field surrounding the wire. In a series rlc circuit containing a resistor, an inductor and a capacitor the source voltage v s is the phasor sum made up of three components, v r, v l and v c with the current common to all three.