1. Here, I am trying to present about Electromagnetic Induction.

2. OBJECTIVES:- (note: they are very shortly briefed ) After complete that lecture we will be able to:- Get some information about Electromagnetic Induction system. What are the requirements for Electromagnetic Induction. We will know about the amount of Induced e.m.f. We will know about Faradays low of Electromagnetic Induction. Direction of Induced e.m.f. (Lenzs Law & Fleming Right Hand Rule)

3. When the Magnetic flux linking with a conductor or coil and changes an e.m.f. is induced in the conductor. If the conductor forms a complete loop or circuit, a current will flow in it, thats called the Electromagnetic Induction.

4. The basic Requirements for Electromagnetic Induction:- 1) The first and basic requirement for electromagnetic induction is the change in Flux linking with the conductor (or coil). 2) The e.m.f. and hence the current in this conductor (or coil) will persist so long ass this change is taking place.

5. Some other important Requirements are The requirement is not only linking the coil with the Flux, the main thing is, if we want to induced some e.m.f. The Flux should be change after linking with coil. No change of Flux ,No e.m.f. Induced in the coil. The change of Flux linking with the conductor and Flux can be cutting in two ways:-

6. 1) One of them The conductor will moved and the magnetic field will Stationary. Use that system the DC generator works.

7. 2) Secondly, The conductor will stationary and the Magnetic field will be moved. That is used for the AC generator.

8. The term N is called flux linkages with Coil. Thus emf induced in a coil is directly proportional to the rate of change of flux linkages. In the same rate of changes flux if we increase the turn of coil then the rate of induced emf will be increase.

9. Amount of Induced e.m.f: The amount of induced e.m.f. in a coil is directly proportional to-- -- 1) the number of turn on the coil, 2) the rate change the Flux linking with coil. Induced emf is Here, N= Number of Turn of Coil = the change of Flux linking by conductor t= time of changing the flux t NN t N eortheChangTimeTakenf uxChangeofFl N geofFluxrateofChanN 12 )12(

10. Faradays Law of Electromagnetic Induction:- Faraday performed a series of experiments to the phenomenon of electromagnetic induction. He performed two laws about electromagnetic induction a known as Faradays law:- First Law: When the Changes Flux linking with a conductor or coil, an emf is Induced in it. Second Law: The magnitude of induced emf in a coil is directly proportional to the rate of change of flux linkages

11. Induced emf Rate of change of flux linksges. Consider a magnet approaching towards a coil. Here we consider two instants at time T1 and time T2. Flux linkage with the coil at time, T1 = N1 Wb Flux linkage with the coil at time, T2 = N2 wb Change in flux linkage = N(2 1) Let this change in flux linkage be, = 2 1 So, the Change in flux linkage = N Now the rate of change of flux linkage = N / t Take derivative on right hand side we will get The rate of change of flux linkage = Nd/dt But according to Faradays law of electromagnetic induction the rate of change of flux linkage is equal to induced emf

12. Direction of Induced emf and Current: The direction of Induced emf and hence current in conductor or coil can be determined by one of the following methods: 1. Lenzs Law 2. Flemings Right hand Rule. 1) Lenzs Law:- Email Lenz, observed that the direction of induced emf has a defined relation to change of magnetic field that produces it. He gave the simple following simple rule:-

13. An Induced Current will flow in such a Direction so as to oppose the cause that produces it. The cause that the change of produces current is the change of flux linking the coil. Therefore, the direction of induced current will be such that its own magnetic field oppose the change in flux that produced the induced current. That means the induced current on its conductor or coil will be the oppose direction of the original flux direction.

14. We know that, the magnetic flux always flow through from North pole to South pole. So, Current will be flow through from South to North.

15. 2) Flemings Right Hand Rule:- This is the Rule of particularly suitable to find the direction of Induced emf and hence current when the conductor moves at right angles to a stationary magnetic field. Stretch out the Four finger, Middle finer and thumb of Your right hand so that they are at right angles to one another.

16. If the forefinger points to direction of the magnetic field, Thumb is the direction of motion the conductor, then the middle finger will point in the direction to the Induced Current.

17. Explanation of Flemings Right Rule:- Consider that, A Conductor is Moving as the direction of Forefinger, the magnetic flux is go through from the north to south pole as the same direction of Thumb finger, now Current will be flow as the same direction of the middle finger.

18. Let, ABCD is a conductor and it is moving through in Clock wise direction magnetic fluxs are going from north pole to south pole. When the conductor is moving flux is cutting by it. When flux is cutting emf is induced by conductor. On the time ABCD conductor is in vertical position flux is cutting and emf induced from DCBA in conductor and it is passing through by the Commutator, the conductor have two terminals there have two carbon brush with two commutators. Commutator is moving With the conductor and induced emf (Current) is passing through by carbon brush to the circuit.

19. After moving sometimes the conductor will in parallel condition, so no flux will be cut by the conductor and no emf will induced in conductor. So, no current will flow. Again when the conductor will be in vertical position on this time magnetic flux will be cut by conductor but this time will be flow the negative current by conductor. And current will be flow from ABCD. The current flowing curve for a full cycle will be like the showing in the figure. That getting current is called AC current.