Electromagnetic Induction

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Electromagnetic Induction by Mind Map: Electromagnetic Induction

1. N = number of turns in coil

2. A = area of surface

3. .

3.1. where f = 1 / T

3.1.1. T = Period of revolution

3.2. AC Generator

3.2.1. Φ = NBAcosθ

3.2.1.1. BUT, θ = ωt

3.2.1.1.1. Hence, Φ = NBAcos ωt

4. Φ = Nϕ

5. Mother

6. ;.

6.1. Product of the magnetic flux density & the area normal to the field through which the field is passing

7. ∆Q = ∆Φ / R

8. Unit: Wb (Weber)

9. Φ = BAcosθ

10. induced emf as B parallel plane of disc and axis of rotation

11. .

11.1. copper disc rotates at frequency f between poles of magnet

12. Units of E: V (Volts of induced current)

13. .

14. l = length of conductor

15. Index - Magnetic Field Direction

16. The induced emf, E, in any closed circuit is equal to the time rate of change of the magnetic flux through the circuit

17. Direction of induced emf is such that it tends to oppose the flux-change causing it, and does oppose it if induced current flows

18. .

19. θ = angle between the magnetic field and the surface S

20. .

21. Magnetic flux ϕ

22. Magnetic flux linkage Φ

22.1. Total flux through the coil

22.2. Unit: Wb (Weber)

22.3. Φ = NBAcosθ

23. Use of search coil to measure B

24. Q = NBA / R

24.1. R = total resistance of circuit

25. Faraday's Law

25.1. E <>< d/dt x (Nϕ)

25.2. Middle Finger - Induced Current Direction

25.2.1. Father

25.2.2. Child

26. Lenz's Law

26.1. E = - dϕ / dt

26.1.1. E = - N d(BAcosθ) / dt

26.1.2. Unit: V (Volts)

26.2. If this were not the case, magnet's velocity and KE would be increased indefinitely, but there is no source for the energy, so COE is violated

26.3. derived from Conservation of Energy

27. Fleming's Right Hand Rule

27.1. Thumb - Force Direction

27.2. B = magnetic flux density

28. Currents that are caused in metals moving in a magnetic field

28.1. can be +ve or -ve

29. EMF induced in Moving Straight Conductor

29.1. E = Blv

29.1.1. v = velocity

29.2. E = 0, when l or v is parallel to B

30. Applications of EMI

30.1. Use of search coil to measure flux density

30.2. Disc Generator

30.2.1. E = Bπr²f

30.3. Eddy Currents

30.3.1. Magnetic Effect

30.3.1.1. can be reduced by creating slots in the plate

30.3.1.1.1. Eddy currents cannot pass through air gaps

30.3.1.2. Follow Lenz Law

30.3.1.2.1. oppose the motion producing them

30.3.2. Heating Effect

30.3.2.1. coil carrying high frequency ac, causes rapidly changing magnetic flux to induce large eddy currents

31. N pole induced in top of solenoid when magnet's North is moved towards solenoid to oppose direction of magnet

31.1. Use Right hand grip rule to determine direction of current

32. Note: If l or v is not perpendicular to the field lines

32.1. Component perpendicular to the field should be used