Electromagnetic Induction Faraday's law in electromagnetic induction
Greetings! My name is Udit Gupta. The topic of discussion is a law given by an eminent scientist which deals with current generating capacity of loop when magnetic field varies across it. My user id on unacademy is: https://unacademy.com/user/udit13
Introduction Have you ever wondered how a card reader reads the magnetically encoded data on a credit card? The information is stored in tiny magnetized regions on the card (on the order of 10-8m) In a card reader, the motion of the credit card moves these tiny magnets past the read/write head, inducing currents in the head that convey the data to a computer. What goes on in the read/write head is an example of electromagnetic induction: A changing magnetic field causes a current in a circuit, even though there's no battery or other obvious source of electromotive force (emf). In this chapter, we discuss the electromotive force (emf) that results from magnetic interactions. Many of the components of present-day electric power systems, including generators, transformers, and motors, depend directly on magnetically induced emfs. These systems would not be possible if we had to depend on chemical sources of emf, such as batteries
Introduction The central principle in this chapter is Faraday's law. This law relates induced emf to changing magnetic flux through a loop, often a closed circuit. We also discuss Lenz's law, which helps us to predict the directions of induced emf's and currents. This chapter discusses the principles that we need to understand electrical energy conversion devices, including motors, generators, and transformers. It also paves the way for the analysis of electromagnetic waves in the upcoming topic.
Faraday's law Meter shows induced current Meter shows zero urrent. The figure shows a bar magnet placed along the axis of a conducting loop containing a galvanometer. There is no current in the loop and correspondingly no deflection in the galvanometer. If we move the magnet towards the loop, there is a deflection in the galvanometer showing that there is an electric current in the loop. If the magnet is moved away from the loop, again there is a current but it is in the opposite direction. The current exists as long as the magnet is moving Meter shows induced current
Faraday's law Faraday studied this behaviour in detail by performing a number of experiments and discovered the following law of nature: Whenever the flux of magnetic field through the area bounded by a closed conducting loop changes, an emf is produced in the loop. The emf is given by dt f B. dS is the flux of the magnetic field through the area. where We shall call the quantity magnetic flux. The SI unit of magnetic flux is called weber which is equivalent to tesla meter2.
Faraday's law The equation given in the previous slide is known as Faraday's law of electromagnetic induction. The flux maybe changed in a number of ways One can change the magnitude of the magnetic field B at the site of the loop, the area of the loop or the angle between the area vector d and the magnetic field B. In any case, as long as the flux keeps changing, the emf is present. The emf so produced drives an electric current through the loop. If the resistance of the loop is R, the current is: E 1 d R R dt The emf induced due to changing flux is called induced emf and current produced by this emf is known as induced current.
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