Electromagnetic Induction
by Boss Magneto
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
3.3. .
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. θ = angle between the magnetic field and the surface S
19. .
20. Magnetic flux ϕ
21. Magnetic flux linkage Φ
21.1. Total flux through the coil
21.2. Unit: Wb (Weber)
21.3. Φ = NBAcosθ
22. Use of search coil to measure B
23. Q = NBA / R
23.1. R = total resistance of circuit
24. Faraday's Law
24.1. E <>< d/dt x (Nϕ)
24.2. Middle Finger - Induced Current Direction
24.2.1. Father
24.2.2. Child
25. Lenz's Law
25.1. E = - dϕ / dt
25.1.1. E = - N d(BAcosθ) / dt
25.1.2. Unit: V (Volts)
25.2. 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
25.3. derived from Conservation of Energy
26. Fleming's Right Hand Rule
26.1. Thumb - Force Direction
26.2. B = magnetic flux density
27. Currents that are caused in metals moving in a magnetic field
27.1. can be +ve or -ve
28. EMF induced in Moving Straight Conductor
28.1. E = Blv
28.1.1. v = velocity
28.2. E = 0, when l or v is parallel to B
29. Applications of EMI
29.1. Use of search coil to measure flux density
29.2. Disc Generator
29.2.1. E = Bπr²f
29.3. Eddy Currents
29.3.1. Magnetic Effect
29.3.1.1. can be reduced by creating slots in the plate
29.3.1.1.1. Eddy currents cannot pass through air gaps
29.3.1.2. Follow Lenz Law
29.3.1.2.1. oppose the motion producing them
29.3.2. Heating Effect
29.3.2.1. coil carrying high frequency ac, causes rapidly changing magnetic flux to induce large eddy currents