Magic Paper Hold a piece of notebook paper just under your lower lip and blow across it. What do you observe?

Bernoulli’s Principle The pressure in a fluid decreases as the fluid’s velocity increases.

Why? PE + KE + P = PE + KE +P (Law of Conservation of Energy)

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Airplane wings generate lift because…

Magnets… North and south poles Attract/repel (similar to charges)

Magnetic Fields (B) Represented by field lines –More lines = stronger field –Loops exit from north and enter south

What makes a magnet a magnet?

Magnetic Domains Group of neighboring electrons’ magnetic fields Point in random directions

Magnetic Domains Picture

Permanent Magnets Metal alloys (iron, nickel, cobalt) Domains permanently aligned

Temporary Magnets Domains align (certain materials only) Temporary magnet created

E and M… Hans Oersted (1820) Moving charge produces a magnetic field

Field Lines Form closed loops around wire

What if wire is coiled (a solenoid)? Intensity of field increased Iron core increases field strength Electromagnet

Electric Motor Conductor between opposite magnetic poles Loop spins due to interaction of magnetic fields Electrical to mechanical

Remember… Oersted - CC wire generates a magnetic field Could the reverse be true?

1831 Faraday and Henry Magnetic field can produce current Conductor or magnet must move

Electric Generator ME to EE Wire loops in magnetic field rotated (wind, water, steam, etc.)

Electromagnetic Induction Current generated due to relative motion of magnet/conductor – Perpendicular – max – Parallel – none

AC Current

Let’s go make some electricity…

AC Current Armature turns at fixed revolutions per second

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Transformers Increase or decrease AC voltage 1º and 2º coil Operation Step-up or step-down