**ELECTROMAGNETIC** INDUCTION Presentation is prepared by: Guided By: Meet Patel(13BEEEM052) Prof. Krishna Chauhan Jaydev Kubavat(13BEEEG049) Electrical Engg. Dept. Mayur Patel(13BEEEM053) S.V.I.T. Vasad. Parth Gupta(13BEEEG013)

**Self Assessment ** learning Elements of Electrical Engineering(2110005)

**certificate** This to certify that Meet Patel(13BEEEM052) Mayur Patel(13BEEEM053) Jaydev Kubavat (13BEEEG049) Parth Gupta(13BEEEG016) Of Electrical-1 has completed their Active learning Assignment for term ending in December 2013 DATE:25/11/2013 Sign of Teacher Head Of Department

**Electromagnetic induction** It is the process by which an emf (voltage) is produced in a wire by a changing magnetic flux. Magnetic flux is the product of the magnetic field and the area through which the magnetic field passes. Electromagnetic induction is the principle behind the electric generator. The direction of the induced current due to the induced emf is governed by Lenz’s Law.

**Faraday’s law** It states that an induced emf is produced by changing the flux, but how could the flux be changed? Turn the field off or on. Move the loop of wire out of the field Rotate the loop to change the angle between the field and the area of the loop.

**Faraday’s Law in equation form:** Where Є = The induced emf (voltage) (V) ΔΦ = The change in flux (Wb) Δt = The change in time (s) N = number of loops.

**The induced emf in the wire will produce a current in the** wire. The magnitude of the induced current is found using Ohm’s Law:

**Application of Faraday’s Law** • Generator

**Faraday’s Law** • Show that when you integrate the emf, e with respect to time you get the average change in flux in time t. Average value

**The Most Important Point of Faraday’s Law** A changing magnetic field produces or creates an electric field. Two types of electric fields. One is created by charge and the other is created by a changing magnetic field.

**Lenz’s Law** The induced current in a wire produces a magnetic field such the flux of the produced magnetic field opposes the original change in flux. In simple terms the wire resists the change in flux and wants to go back to the way things were.

**x x x x x x x x x x x x x x x x** n n n q A (c)q = 600 A = 40 cm2 (a)q = 00 (b)q = 900 Example A current loop has an area of 40 cm2 and is placed in a 3-T B-field at the given angles. Find the flux F through the loop in each case. (a)F = BA cos 00 = (3 T)(0.004 m2)(1); F = 12.0 mWb (b)F = BA cos 900 = (3 T)(0.004 m2)(0); F = 0 mWb (c)F = BA cos 600 = (3 T)(0.004 m2)(0.5); F = 6.00 mWb

**Lenz’s Law** • The direction of the emf and thus the current is given by Lenz’s law. The statement in bold in the center of page 789 is a statement of Lenz’s law. Use this to find the direction of the current. If you are looking down on the loop from above, is the current flowing clockwise or counter clockwise? Explain.

**Lenz’s Law** The magnetic is moving away from the coil so the magnetic field is decreasing, thus the current is in a direction to off-set the decrease. The magnetic is moving toward the coil so the magnetic field is increasing, thus the current is in a direction to off-set the increase.

**B** I Down I Up Down Up v F B B F v Induced Current When a conductor moves across flux lines, magnetic forces on the free electrons induce an electric current. Right-hand force rule shows current outward for down and inward for up motion. (Verify)

**Magnetic Flux Density** Df DA Magnetic Flux density: • Magnetic flux lines Fare continuous and closed. • Direction is that of the B vector at any point. When area A is perpendicular to flux: The unit of flux density is the weber per square meter.

**Important Terms.** alternatingcurrent - electric current that rapidly reverses its direction electricgenerator - a device that uses electromagnetic induction to convert mechanical energy into electrical energy electromagneticinduction - inducing a voltage in a conductor by changing the magnetic field around the conductor induced current - the current produced by electromagnetic induction induced emf - the voltage produced by electromagnetic induction

**Faraday’slawofinduction - law which states that a voltage** can be induced in a conductor by changing the magnetic field around the conductor Lenz’s law - the induced emf or current in a wire produces a magnetic flux which opposes the change in flux that produced it by electromagnetic induction magnetic flux - the product of the magnetic field and the area through which the magnetic field lines pass. motional emf - emf or voltage induced in a wire due to relative motion between the wire and a magnetic field

**THANK YOU…..**