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1, , Electromagnetic Induction, (05 marks), Electromagnetic induction : The relative motion between a coil and a magnet generates electric current, in the coil. This phenomenon is called electromagnetic induction., Michael Faraday made the discovery of electromagnetic induction in 1831., , Induced current : Whenever there is a relative, motion between a coil and magnet, a current is, induced in the coil. This current is called induced, current., Induced emf (or Induced potential difference or, Induced voltage) : Whenever there is a relative, motion between a coil and magnet, a potential, difference is developed across the coil. This, potential difference is called induced emf (or, induced potential difference or induced voltage)., Electromotive force (emf) : Electromotive force is the difference in the potential that tends to give rise to, an electric current. It is equal to the terminal potential difference when no current flows., The results of Faraday's experiment on electromagnetic induction :, 1. Whenever there is a relative motion between a coil and a magnet, an induced current flows in the, coil., 2. Induced current in the coil lasts as long as there is change in the number of magnetic lines of, force linked with the coil., 3. The strength of the induced emf is directly proportional to the rate of change of magnetic lines of, force linked with the coil., When a conductor moves in a magnetic field, a current is induced in the conductor. The induced current in, the conductor is maximum when the direction of motion of the conductor is perpendicular to the, direction of the magnetic field., The direction of induced current developed in a straight conductor moving in a magnetic field can be, determined by Fleming's Right Hand Rule., Fleming's Right Hand Rule :, If the thumb, forefinger and middle finger of right hand are held mutually perpendicular to each other, such that the thumb shows the direction of motion of the conductor and the forefinger shows the direction, of the magnetic field, then the middle finger will show the direction of the induced current in, the conductor., Prepared by Johnson Khundrakpam, Asst. Teacher, KMBHSS Block (A), , ☎️ 9555985815

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2, , The principle of electromagnetic induction is used in the construction of electric generators,, microphones, electric guitars, etc., Q. What is electromagnetic induction? (2012, 2017, 2019), Q. Define induced current and induced emf., Q. A coil of copper wire is connected to a galvanometer. What would happen if a bar magnet is, a) pushed into the coil very slowly?, b) pushed into the coil very rapidly?, c) held at rest inside the coil?, d) pulled out again rapidly?, Ans., a) When the bar magnet is pushed into the coil very slowly, the needle of the galvanometer would, slightly deflect due to the presence of a negligible induced current in the coil., b) When the bar magnet is pushed very rapidly into the coil, the needle of the galvanometer would, highly deflect in one direction., c) When the bar magnet is held at rest inside the coil, there would be no deflection in the needle of, the galvanometer., d) When the bar magnet is pulled out again rapidly, there would be a momentary deflection in the, needle of the galvanometer in a direction opposite to that when the bar magnet was pushed., Q. State the three results of Faraday's experiment on electromagnetic induction. (2010), Q. State Fleming's Right Hand Rule. (2019), Q. What is the purpose of Fleming's Right Hand Rule?, Ans. The purpose of Fleming's Right Hand Rule is to determine the direction of induced current, developed in a straight conductor moving in a magnetic field., Q. Name three devices in which the principle of electromagnetic induction is used for construction., Ans. Electric generators, electric guitars, microphones, Q. When is the induced current developed in a straight conductor moving in a magnetic field, maximum?, Ans. The induced current developed in a straight conductor moving in a magnetic field is maximum when, the direction of motion of the conductor is perpendicular to the direction of the magnetic field., Q. Two circular coils A and B are placed close to each other. If the current in coil A is changed, will, some current be induced in the coil B? Give reason for your answer. (NCERT), Ans. Yes, some current will be induced in the coil B. When the current in coil A is changed, the strength, of the magnetic field produced by it is also changed. Hence, the change in the number of magnetic field, lines linked with coil B induces an electric current in the coil B., , Prepared by Johnson Khundrakpam, Asst. Teacher, KMBHSS Block (A), , ☎️ 9555985815