Flux, Induction and Electromagnetic Waves by ves88494

VIEWS: 101 PAGES: 24

									Flux, Induction and Electromagnetic Waves

                John Mahoney
 Physics Department, Complexity Sciences Center
                   UC Davis

                August 28, 2008




                                                  1 / 17
Flux
What is Flux?
Magnetic Flux
illustrated
Magnetic Flux
Definition
Solenoid
Solenoid

Induction
Electromagnetic
Waves             Flux




                         2 / 17
                  What is Flux?

Flux
What is Flux?
                  Recall definition of flux from Physics 7B...
Magnetic Flux
illustrated
Magnetic Flux
Definition
Solenoid
Solenoid

Induction
Electromagnetic
Waves




                                                               3 / 17
                  What is Flux?

Flux
What is Flux?
                  Recall definition of flux from Physics 7B...
Magnetic Flux
illustrated
Magnetic Flux
Definition
                  Flux is ‘the amount of some stuff that passes per second per
Solenoid          area’.
Solenoid

Induction
Electromagnetic
Waves




                                                                          3 / 17
                  What is Flux?

Flux
What is Flux?
                  Recall definition of flux from Physics 7B...
Magnetic Flux
illustrated
Magnetic Flux
Definition
                  Flux is ‘the amount of some stuff that passes per second per
Solenoid          area’.
Solenoid

Induction
Electromagnetic   Magnetic flux is roughly ‘the number of magnetic field lines
Waves
                  that pass through an opening’.




                                                                          3 / 17
                  Magnetic Flux illustrated

Flux
What is Flux?
Magnetic Flux
illustrated
Magnetic Flux
Definition
Solenoid
Solenoid

Induction
Electromagnetic
Waves




                                              4 / 17
                  Magnetic Flux Definition

Flux
What is Flux?
Magnetic Flux
                            Φ = B × A × cos(θ)
illustrated
Magnetic Flux
Definition
Solenoid
Solenoid

Induction
Electromagnetic
Waves




                                                 5 / 17
                  Magnetic Flux Definition

Flux
What is Flux?
Magnetic Flux
                            Φ = B × A × cos(θ)
illustrated
Magnetic Flux
Definition
Solenoid
Solenoid                 Don’t confuse this Φ with the total phase...
Induction
Electromagnetic
Waves




                                                                        5 / 17
                  Solenoid

Flux
What is Flux?
Magnetic Flux
illustrated
Magnetic Flux
Definition
Solenoid
Solenoid

Induction
Electromagnetic
Waves




                             6 / 17
                  Solenoid

Flux
What is Flux?
Magnetic Flux
illustrated
Magnetic Flux
Definition
Solenoid
Solenoid

Induction
Electromagnetic
Waves




                             7 / 17
Flux

Induction
What is magnetic
induction?
Derive magnetic
induction
Lenz’s Law
Electromagnetic
Waves

                   Induction




                               8 / 17
                   What is magnetic induction?

Flux
                         changing magnetic fields create electric fields!
Induction
What is magnetic
induction?
Derive magnetic
induction
Lenz’s Law
Electromagnetic
Waves




                                                                          9 / 17
                   What is magnetic induction?

Flux
                         changing magnetic fields create electric fields!
Induction
What is magnetic
induction?
Derive magnetic
induction
Lenz’s Law         changing magnetic flux creates an electric potential driving
Electromagnetic
Waves
                                  current around the loop!




                                                                           9 / 17
                   Derive magnetic induction

Flux
                   Look at loop moving out of a B field.
Induction
What is magnetic
induction?
Derive magnetic
induction
Lenz’s Law
Electromagnetic
Waves




                                                          10 / 17
                   Lenz’s Law

Flux
                   Use the formula to figure out the magnitude of the induced
Induction
What is magnetic                             EMF.
induction?
Derive magnetic
induction
Lenz’s Law
Electromagnetic
Waves




                                                                        11 / 17
                   Lenz’s Law

Flux
                   Use the formula to figure out the magnitude of the induced
Induction
What is magnetic                             EMF.
induction?
Derive magnetic
induction
Lenz’s Law
Electromagnetic
Waves
                   Use Lenz’s Law to figure out the direction around the loop.




                                                                         11 / 17
                   Lenz’s Law

Flux
                   Use the formula to figure out the magnitude of the induced
Induction
What is magnetic                             EMF.
induction?
Derive magnetic
induction
Lenz’s Law
Electromagnetic
Waves
                   Use Lenz’s Law to figure out the direction around the loop.

                    ‘When the magnetic flux changes, current will attempt to
                   flow around the loop so as to create an additional magnetic
                           field that counteracts this change in flux.’




                                                                         11 / 17
Flux

Induction
Electromagnetic
Waves
What if...?
Light needs no
medium
EM spectrum
Polarization
Malus’ Law
                  Electromagnetic Waves




                                          12 / 17
                  What if...?

Flux
                                  We already know that
Induction
Electromagnetic
                        changing magnetic fields create electric fields!
Waves
What if...?
Light needs no
medium
EM spectrum
Polarization
Malus’ Law




                                                                         13 / 17
                  What if...?

Flux
                                  We already know that
Induction
Electromagnetic
                        changing magnetic fields create electric fields!
Waves
What if...?
Light needs no
medium
EM spectrum                               but what if
Polarization
Malus’ Law
                        changing electric fields create magnetic fields!?




                                                                          13 / 17
                  Light needs no medium

Flux

Induction
Electromagnetic
Waves
What if...?
Light needs no
medium
EM spectrum
Polarization
Malus’ Law




                                          14 / 17
                  EM spectrum

Flux

Induction
Electromagnetic
Waves
What if...?
Light needs no
medium
EM spectrum
Polarization
Malus’ Law




                                15 / 17
                  Polarization

Flux

Induction
Electromagnetic
Waves
What if...?
Light needs no
medium
EM spectrum
Polarization
Malus’ Law




                                 16 / 17
                  Malus’ Law

Flux                        y
Induction
Electromagnetic
                                   θ1
Waves
What if...?
Light needs no
                                         x ∆θ θ2
medium
EM spectrum
Polarization
Malus’ Law




                       I0                            z
                                  Polarizer
                                              I
                                Iout = Iincos2(∆θ)

                                                         17 / 17

								
To top