Magnetic Induction and Faraday’s Law and Alternating Current, Study notes of Physics

Download Magnetic Induction and Faraday’s Law and Alternating Current and more Study notes Physics in PDF only on Docsity! Magnetic Induction and Faraday’s Law and Alternating Current PHYSICS II SY 2021-2022 Electromagnetic Induction was discovered by Michael Faraday in 1831, and James Clerk Maxwell mathematically described it as Faraday’s law of induction. Electromagnetic induction is the process by which a current can be induced to flow due to a changing magnetic field. This either happens when a conductor is placed in a moving magnetic field or when a conductor is constantly moving in a stationary magnetic field. The significance of this discovery is a way of producing electrical energy in a circuit by using magnetic fields and not just batteries. Everyday machines like motors, generators and transformers work on the principle of electromagnetic induction. Magnetic Induction and Faraday’s Law Electrostatic fields - arise from a potential difference or voltage gradient, and can exist when charge carriers, such as electrons are stationary. Magnetic fields arise from the movement of charge carriers, that is, from the flow of current. There is an important distinction between the electric field induced by a changing magnetic field and the electrostatic field produced by a fixed charge distribution. Specifically, the induced electric field is nonconservative because it does net work in moving a charge over a closed path, whereas the electrostatic field is conservative and does no net work over a closed path. Hence, electric potential can be associated with the electrostatic field, but not with the induced field. The following equations represent the distinction between the two types of electric field: (induced) (electrostatic) The induced electric field is a nonconservative field that is generated by a changing magnetic field. The field cannot be an electrostatic field because if the field were electrostatic, and. hence conservative, the line integral of over a closed loop would be zero. Magnetic Induction and Faraday’s Law Electromotive force - is defined as the electric potential produced by either electrochemical cell or by changing the magnetic field. (EMF is the commonly used acronym for electromotive force.) A generator or a battery is used for the conversion of energy from one form to another. In these devices, one terminal becomes positively charged while the other becomes negatively charged. Therefore, an electromotive force is a work done on a unit electric charge. Potential difference - The potential difference between two points in an electrical or electronic circuit represents the work involved or the energy released in the transfer of a unit quantity of electricity from one point to the other. The key point is that EMF is the cause( i.e. it is the driving force), whereas potential difference is the result of the EMF. Eletromotive force Electromotive force formula; Where, V is the voltage of the cell I is the current across the circuit r is the internal resistance of the cell ε is the electromotive force The unit for electromotive force is Volt. Eletromotive force Faraday’s First Law of Electromagnetic Induction The discovery and understanding of electromagnetic induction are based on a long series of experiments carried out by Faraday and Henry. From the experimental observations, Faraday concluded that an emf is induced when the magnetic flux across the coil changes with time. Therefore, Faraday’s first law of electromagnetic induction states that “Whenever a conductor is placed in a varying magnetic field, an electromotive force is induced. If the conductor circuit is closed, a current is induced, which is called induced current.” Method to change the magnetic field: - By rotating the coil relative to the magnet. - By moving the coil into or out of the magnetic field. - By changing the area of a coil placed in the magnetic field. - By moving a magnet towards or away from the coil. Faraday’s Second Law of Electromagnetic Induction Faraday’s second law of electromagnetic induction states that “The induced emf in a coil is equal to the rate of change of flux linkage.” The flux linkage is the product of the number of turns in the coil and the flux associated with the coil. The formula of Faraday’s law is given below: The rate of change of flux linkage But according to Faraday’s law of electromagnetic induction, the rate of change of flux linkage is equal to induced emf. Considering Lenz’s law Where; ε is the electromotive force is the magnetic flux N is the number of turns t is the change in time From the above equation, we can conclude the following -Increase in the number of turns in the coil increases the induced emf -Increasing the magnetic field strength increases the induced emf -Increasing the speed of the relative motion between the coil and the magnet, results in the increased emf Faraday’s Law Faraday's law is when the number of magnetic field lines that pass through a loop of wire changes, an induced emf appears in the loop. Another way of saying this is that when the flux that passes through a wire loop changes, an emf is induced in the loop: If the loop of wire has N turns, then: Flux is defined as the product of area times the electric field. If the field B is perpendicular to the loop and the area A is constant, we can rewrite this equation as: Calculate the magnitude of the induced emf, when the magnet is thrust into the a coil, the single loop coil has a radius of 7 cm and the average value of magnetic flux increases from 0.150 T to 0.350 T in 0.2 s. Given; N= 1t= 0.2 s Solution; = = 0.0154 V Sample Problem A coil with 60 turns is wrapped around a square frame with area 0.15m2. The coil is immersed inside a magnetic field that changes at the rate of 0.01 T/s. What is the induced emf in the coil? Given; N= 60 A= 0.15m2 = 0.01 t/s Solution; we eliminate the negative because directions are not specified. = 0.09 V Sample Problem Alternating current (AC) - a current that changes its magnitude and polarity at regular intervals of time. It can also be defined as an electrical current that repeatedly changes or reverses its direction opposite to that of Direct Current or DC which always flows in a single direction. Alternating Current Electromagnetic induction. BYJUS. https://byjus.com/physics/electromagnetic-induction/#:~:text=Electromagnetic%20Induction%20is%20a %20current,in%20a%20stationary%20magnetic%20field. Tech target contributor. Electrostatic field. TechTarget. https://www.techtarget.com/whatis/definition/electrostatic-field#:~:text=Electrostatic %20fields%20arise%20from%20a,from%20the%20flow%20of%20current. Electromotive force BYJUS. https://byjus.com/physics/electromotive-force/ Electromotive Force EMF & Potential Difference. Eletronics notes. https://www.electronics-notes.com/articles/basic_concepts/voltage/ electromotive-force-emf-potential-difference.php Induced electric field. Open Stax. https://openstax.org/books/university-physics-volume-2/pages/13-4-induced-electric-fields Induced emf. BYJUS. https://byjus.com/questions/define-induced-emf/ Electrical4u(2021 June 24). Faraday’s Laws of Electromagnetic Induction: First & Second Law. Electrical 4 U. https://www.electrical4u.com/faraday-law-of-electromagnetic-induction/ Faradays Law. BYJUS. https://byjus.com/physics/faradays-law/ Britannica, T. Editors of Encyclopaedia (2021, April 2). alternating current. Encyclopedia Britannica. https://www.britannica.com/science/alternating-current Alternating current. BYJUS.https://byjus.com/jee/alternating-current/ Maria El-Amin. Solving Problems Involving Emf and Magnetic Field. Study.com. https://study.com/skill/learn/solving-problems-involving-emf-and- magnetic-field-explanation.html Bibliography Electromagnetic induction 2017. BYJUS, accessed on 30 May 2022. https://cdn1.byjus.com/wp-content/uploads/2018/11/physics/wp- content/uploads/2017/11/Electromagnetic-Induction-37.jpg Faradays law 2017. BYJUS, essed on 30 May 2022. https://cdn1.byjus.com/wp-content/uploads/2018/11/physics/2017/11/30 062623/Farady_s-law.jpg Alternating curent 2021. BYJUS,accessed on 31 May 2022. https://cdn1.byjus.com/wp-content/uploads/2021/04/Alternating- CurrentArtboard-1-copy-8.png Photo Credits