1. Electromagnetic Induction

2. Electromagnetic Induction
Known: An electric current produces a magnetic field
Known: A wire moving through (perpendicular to) a magnetic field will develop a potential difference across its ends (Induced emf)
More difficult? Producing a current…

3. Observations What happens to the current when:
North end moved into the loop?
North end moved out of the loop?
South end moved into the loop?
South end moved out of the loop?
North end held above the plane of the loop?
Magnet held inside the loop?
Magnet moved in/out of the loop at a different speed than before?

4. Variables that affect current:
As these increase, so will the current:
The relative speed of the magnet with respect to the loop/coil
Strength of the magnetic field
Number of turns in the coil
Area of the loop
ALSO:
Angle of the magnetic field relative to the plane of the loop.
At an angle 90° (field perpendicular to the plane of the loop), the current will be the maximum possible for the conditions

5. Michael Faraday British Physicist and Chemist—born 1791, died 1867
Self-taught…discovered many concepts, had difficulties with some of the math 
Discovered Electromagnetic Induction in 1831
(also devised the laws relating to electrolysis and the deposition of ions onto metals through the use of electricity)
Found the connecting link between each of the observations we just made…
The relevant law that bears his name (Faraday’s Law) relates to electromagnetism

6. Magnetic Flux Φ=𝐵∙𝐴𝑐𝑜𝑠𝜃
The strength of the magnetic field crossing the plane of a loop of area, A
Φ=𝐵∙𝐴𝑐𝑜𝑠𝜃
B = magnetic field strength
A = area of the loop
q = angle between the magnetic field direction and the normal to the plane of the loop

7. Magnetic Flux Units of flux = Weber (Wb)
Conceptual visualization: flux is the number of magnetic field lines that are passing through the plane of the loop
Increase the flux by:
Increasing the area of the loop
Increasing the strength of the field (more field lines…)
Making the loop and field lines more perpendicular

8. Magnetic Flux Linkage
Same as magnetic flux…but specifically when there is more than 1 loop in a coil.
Φ=𝑁∙𝐵∙𝐴𝑐𝑜𝑠𝜃
N = number of loops in the coil

9. Faraday’s Law
The induced emf is equal to the (negative value for) rate of change of magnetic flux:
𝜀=−𝑁 ∆Φ ∆𝑡
The induced emf, therefore, can cause a current in a conducting wire…but this will ONLY happen when there is a changing magnetic flux!