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)

Animation

Airplane wings generat

e lift becaus

e…

Magnets…

North and south polesAttract/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 fieldsPoint 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 increasedIron core increases field strengthElectromagnet

Electric Motor

Conductor between opposite magnetic polesLoop spins due to interaction of magnetic fieldsElectrical to mechanical

Remember…

Oersted - CC wire generates a magnetic fieldCould the reverse be true?

1831

Faraday and HenryMagnetic field can produce currentConductor or magnet must move

Electric Generator

ME to EEWire 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

Picture

Transformers

Increase or decrease AC voltage1º and 2º coilOperationStep-up or step-down