Diploma i boee u 4 magnetism and electromagnetic effect
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here i attached unit 4 of subject basics of electrical engineering
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Diploma i boee u 4 magnetism and electromagnetic effect
- 1. Topic: Magnetism and Electromagnetic effect Course: Diploma Subject:Basics of Electrical Engineering Unit: 4
- 2. • Force on current carrying conductor in magnetic field • Concept about electrical and magnetic circuit • Magnetization curve • Faradays and Lenz’s laws • Flemings left and Right hand rule • Induced emf and types • Administrative management/Fayol’s 14 principles of management Topics
- 3. Force on current carrying conductor in magnetic field Fig 1
- 4. the figure, a conductor lying vertically in a uniform horizontal magnetic field of strength H. If l is the length of the conductor tying within this magnetic field and i is the current through it, then the force experienced by the conductor will be F = B.i.l Newton = μ0.μr.H.i.l Newton The direction of the force F can also be determined by Flemming's Left Hand Rule. As per this rule, if any one holds out his or her hand with fore finger, second finger and thumb at right angle to each other, then his or her fore-finger will indicate the direction of magnetic field, the second finger will indicate the direction of flow of current and the thumb will give the direction of force or motion of the conductor.In this case the force experienced by the conductor will be F = B.i.l.sin(θ) Newton.
- 5. Comparison between Electric and Magnetic Circuits Fig 2
- 7. Parallel Magnetic Circuit l2l1 l3 I N S1 S2S3 + - NI 1 3 2 I II Loop I NI = S33 + S11 = H3l3 + H1l1 Loop II NI = S33 + S22 = H3l3 + H2l2 Loop III 0 = S11 + S22 = H1l1 + H2l2 Fig 4 self making
- 8. Magnetic Circuit with Air Gap lc i N lg + F - c g g g g c c c ggcc gC g0 g g cc c c A B A B densityFlux lHlHNi Ni A l A l ; ; Fig 5 self making
- 9. Series circuits A series circuit has only one current path Current through each component is the same In a series circuit, all elements must function for the circuit to be complete Fig 6
- 10. Parallel circuits A parallel circuit has more than one current path branching from the energy source Voltage across each pathway is the same. In a parallel circuit, separate current paths function independently of one another. For parallel voltage sources, the voltage is the same across all batteries, but the current supplied by each element is a fraction of the total current Fig 7
- 11. Magnetization Curve HB r0 Behavior of flux density compared with magnetic field strength, if magnetic intensity H increases by increase of current I, the flux density B in the core changes as shown. Fig 8
- 12. Faraday’s Law • Moving the magnet changes the flux B (1). • Changing the current changes the flux B (2). • Faraday: changing the flux induces an emf. i di/dt S EMF N S i v e = - dB /dt The emf induced around a loop equals the rate of change of the flux through that loop Faraday’s law 1) 2)
- 13. Lenz’s Law • Faraday’s law gives the direction of the induced emf and therefore the direction of any induced current. Lenz’s law is a simple way to get the directions straight, with less effort. • Lenz’s Law: The induced emf is directed so that any induced current flow will oppose the change in magnetic flux (which causes the induced emf). This is easier to use than to say ... Decreasing magnetic flux emf creates additional magnetic field Increasing flux emf creates opposed magnetic field
- 14. Fleming's Right-Hand Rule • The Thumb represents the direction of Motion of the conductor. • The First finger represents the direction of the Field. (north to south) • The Second finger represents the direction of the induced or generated Current (the direction of the induced current will be the direction of conventional current; from positive to negative). Fig 11
- 15. Fleming's Left-Hand Rule • A left hand can be held, as shown in the illustration, so as to represent three mutually orthogonal axes on the thumb, first finger and middle finger. • Each finger is then assigned to a quantity (mechanical force, magnetic field and electric current). The right and left hand are used for generators and motors respectively. Fig 12
- 16. Induced emf • Dynamically Induced emf • Statically Induced emf Dynamically Induced emf By moving the conductor keeping the magnetic field system stationary, thus emf induced in the conductor is called Dynamically Induced emf
- 17. Statically Induced emf • The emf induced by variation of flux is termed as Statically Induced emf • In this case conductor is held stationary and magnetic field varies. • Two Types : 1) Self Induced emf 2) Mutually Induced emf
- 18. 1) Self Induced emf Fig 13
- 19. 2) Mutually Induced emf Fig 14
- 20. REFRENCES : IMAGES • https://www.google.co.in/url?sa=i&rct=j&q=&esrc=s&sour ce=images&cd=&cad=rja&uact=8&ved=0CAcQjRw&url=htt p%3A%2F%2Fwww.slideshare.net%2Fchristaines%2Fcapaci tors-1191029&ei=YOKcVL- aOYWpuwSP04LQCQ&bvm=bv.82001339,d.c2E&psig=AFQj CNGCmbflzcJLZ_sLvIHz0EvVB0OgMw&ust=1419654109104 944 • https://www.google.co.in/url?sa=i&rct=j&q=&esrc=s&sour ce=images&cd=&cad=rja&uact=8&ved=0CAcQjRw&url=htt p%3A%2F%2Fen.wikipedia.org%2Fwiki%2FTypes_of_capaci tor&ei=b- acVJCWNs6duQS44YKICQ&bvm=bv.82001339,d.c2E&psig= AFQjCNF0wwlQgan1b5NXe- KMhMkK4FTG8A&ust=1419655106019885
- 26. REFERENCE • B.L.Theraja, “Electrical Technology Vol.1”, S.Chand Publication. • D.P.Kothari, “Basic Electrical Engineering”, Tata McGraw-Hill publication.