1. Guided By: Prepared By: Hitesh S. Patel131120109056 MAHADIK SAGAR 131120109081 PATEL SHITALBEN 131120109089 RANA AENISH 131120109095 SHAH MANISHKUMAR 131120109082 PATEL VIDHI Elements of Electrical Engineering

2. Statically induced EMF (a) mutually induced e.m.f.- The e.m.f. induced in coil due to change of flux produced by another (neighboring) coil linking with its called mutually induced e.m.f. Fig 1, when switch closed the magnetic flux produced through B. As current through A change flux link also changed. Fig.2 when switch closed then the saturation is reversed than fig 1. Where M is a constant of proportionality and is called mutual inductance of coil.

3. (b) self-induced e.m.f.- The e.m.f. induced in a coil due to change of flux produced by it linking with its own turn is called self induced emf. Consider a coil having N turn. When current I passing through coil, the flux Ǿ produced by its own turns. The direction of this induced e.m.f. (as given by Lenz’s law) would be such as to oppose any change of flux which is, in fact, the very cause of its production. Hence, it is also known as the opposing or counter e.m.f. of self-induction. Where L is constant of proportionality and is called coefficient of self inductance of coil.

4. dynamically induced EMF When A cuts across at right angles to the flux. Suppose ‘l’ is its length lying within the field and let it move a distance dx in time dt Then area = l dx and flux cut = l dx X B web So change in flux = Bldx web

5. Self inductance The coefficient of self-induction of a coil is defined as the weber-turns per ampere in the coil By ‘weber-turns’ is meant the product of flux in webers and the number of turns with which the flux is linked. In other words, it is the flux- linkages of the coil. (1) First method: Consider a coil of N turns carrying a current i, produces a flux Ǿ linking with coil. According to faraday’s law, the e.m.f. induced in a coil is given by

6. For a coil of non-magnetic core, the flux is directly proportional to the current. So Now Where L = self inductance of coil, so

7. (2) Second method: If the number of turns of the coil and physical dimension are known the self inductance of the coil. From equation (1) _______(1) _______(2) _______(3)

8. Electric field When a charged body is placed at some place in space, a region surrounding this body under stress. If charge (+ ve or – ve) is brought in to stressed region, a force of attraction or repulsion according to coulomb’s law. This stressed region around a charge body is called electric field. -ve charged body +ve charged body

9. When there are two different charges- force attraction. When same equal charge – force repulsion. Properties of Electric lines of force: (1) Line of force always originate from + ve charge & terminate at – ve charge. (2) They always enter and leave the conducting surface. (3) They always parallel & never cross each other. (4) The lines travelling same direction repel each other, while travelling opposite ….direction attraction each other. (5) They passed through only insulating medium between the charge.

10. THANK YOU