1. Thursday(03/19): Ch.24 - Intro. to Magnetic Fields and Force.

HW: Read and Study pages 643-51, then solve problems 73, 75, 77, and

79 on page 666.

2. Friday(03/20): The Mass Spectrometer, Force on a Current, and

Magnetic Field of a Current. HW: Read and Study pages 652-63, then solve

problems 83, 85, 87, and 90 on page 667.

3. Monday(03/23): LAB on Magnetic Field of a Magnet. HW: Process lab

data and write lab report, Due Wednesday.

4. Tuesday(03/24): Ch.25 - Electromagnetic Induction, Induced and

Motional Emf, and Magnetic Flux. HW: Read and Study pages 671-78,

then solve problems 60, 61, 64, and 68 on page 692.

5. Wednesday(03/25): Continue with Electromagnetic Induction, Induced

and Motional Emf, and Transformers. HW: Read and Study pages 679-89,

then solve problems 72, 81, 83, and 87 on page 693.

6. Thursday(03/26): Review for Ch.24-25. HW: Complete Review Handout.

Have a Safe and Restful Spring Break (March 27 - April 5). See you when

school starts again on April 6th.

7. Monday(04/06): Ch.25 & 26 - Interactions of Electric and Magnetic Fields

and Matter. Magnetic Fields in Space. HW: Read and Study pages 697-717,

then solve problems 46, 48, 50, 54, and 57 on page 719.  

8. Tuesday(04/07): Magnetic Flux and Electromagnetic Induction.

HW: Complete Review Handout.

9. Wednesday(04/08):  LAB on Magnetic Field of a Coil. HW: Process lab

data and write lab report, Due Tuesday.

10. Thursday(04/09): Review I for Ch.24-25-26. HW: Complete Review

Handout.

11. Friday(04/10): No School. HW: Finish all assigned work.

12. Monday(04/03): Review for II Ch.24-25-26. HW: Complete Review

Handout.

13. Tuesday(04/14): TEST on Ch.24-25-26. HW: Go to website and

study notes, graphics, and links for Ch.27 - Quantum Theory.

900 BC - Magnus, a Greek shepherd, walks across a field of black stones

which pull the iron nails out of his sandals and the iron tip from his

shepherd's staff (authenticity not guaranteed). This region becomes

known as Magnesia.

600 BC - Thales of Miletos rubs amber (elektron in Greek) with cat fur and

picks up bits of feathers.

1269 - Petrus Peregrinus of Picardy, Italy, discovers that natural spherical

magnets (lodestones) align needles with lines of longitude pointing between

two pole positions on the stone.

1600 - The man who began the science of magnetism in earnest was William

Gilbert (1540 - 1603) whose book "De Magnete" was published in 1600.

Gilbert studied at St. John’s College, Cambridge, and became England’s

leading doctor, President of the Royal College of Physicians, and Queen

Elizabeth’s personal physician. At the same time, he worked on magnetism,

and after seeing his book Galileo pronounced Gilbert "great to a degree that

is enviable", not the sort of thing Galileo said too often.

1644 - Rene Descartes theorizes that the magnetic poles are on the central

axis of a spinning vortex of one of his fluids. This vortex theory remains

popular for a long time, enabling Leonhard Euler and two of the Bernoulli's to

share a prize of the French Academy as late as 1743.

1750 - John Michell discovers that the two poles of a magnet are equal in

strength and that the force law for individual poles is inverse square.

1774 – Anton Mesmer became interested in the effects of magnets on the body

and believed that he had discovered an entirely new principle of healing

involving "animal magnetism". This "animal magnetism" that he used was

different from physical magnetism in that he believed that he could "magnetise"

paper, glass, dogs and all manner of other substances.

1820 - Jean-Baptiste Biot and Felix Savart show that the magnetic force exerted

on a magnetic pole by a wire falls off like 1/r and is oriented perpendicular to

the wire.

1825 - Ampere publishes his collected results on magnetism. His expression for

the magnetic field produced by a small segment of current is different from that

which follows naturally from the Biot-Savart law by an additive term which

integrates to zero around closed circuit. It is unfortunate that electrodynamics

and relativity decide in favor of Biot and Savart rather than for the much more

sophisticated Ampere, whose memoir contains both mathematical analysis and

experimentation, artfully blended together.

1846 - Faraday, inspired by his discovery of the magnetic rotation of light,

writes a short paper speculating that light might electro-magnetic in nature.

He thinks it might be transverse vibrations of his beloved field lines. He

also discovers diamagnetism. He sees the effect in heavy glass, bismuth,

and other materials.

1847 - Weber proposes that diamagnetism is just Faraday's law acting on

molecular circuits. In answering the objection that this would mean that

everything should be diamagnetic he correctly guesses that diamagnetism is

masked in paramagnetic and ferromagnetic materials because they have

relatively strong permanent molecular currents. This work rids the world of

magnetic fluids.

1850 - William Thomson (Lord Kelvin) invents the idea of magnetic

permeability and susceptibility.

1895 - Pierre Curie experimentally discovers Curie's law for paramagnetism

and also shows that there is no temperature effect for diamagnetism.

1911 - Kamerlingh Onnes makes a momentous discovery of the phenomenon

of superconductivity in pure metals such as mercury, tin and lead at very low

temperatures, and following from this the observation of persisting currents.

WEBSITE NOTES: Ch. 24-25-26. Magnetic Forces, Magnetic Fields, and

Electromagnetic Induction.

1. The force F produced by a magnetic field on a single charge depends upon

the speed v of the charge, the strength B of the field, and the magnitude of

the charge q, with F = qvBsinθ. θ is the smaller angle between v and B. 

2. To find the direction of the force, use the First Right-Hand Rule with your

fingers in the direction of B, and your thumb in the direction of v. The force

will come out of the palm of your hand

3. If the charged particle moves parallel to the field lines (θ = 0), then the

magnetic force on the particle is zero. If a charged particle is moving

perpendicular to a uniform magnetic field, the path of the charged particle is

an arc (or circle).

4. The strength of the magnetic field depends on the current I in the wire and

r, the distance from the wire. The equation is B=μ_oI∕(2πr) , with the constant

μ_o, "mu naught", given as μ_o = 4π x 10^-7 Tm/A .

5. The constant is the permeability of free space. The reason it does not

appear as an arbitrary number is that the units of charge and current

(coulombs and amps) were chosen to give a simple form for this constant.

6. The magnetic force is the source of the centripetal force on the charged

particle. This relationship can be used to find the radius of the arc when we

set the equations equal to one another,  mv²/r = qvB , and solve for r.

7. Since the magnetic force is perpendicular to the velocity of the charged

particle, the force does not cause the speed of the particle to change, only

its direction. Thus, no work is done by the magnetic force on the charged

particle.

8. In regards to forces due to magnetic fields, Ampere found that a force is

exerted on a current-carrying wire in a magnetic field, F = BILsinθ, where

B is the magnetic field in N/Am, I is the current, L is the length of wire

in meters, and θ is the angle.

9. If the direction of the current is perpendicular to the field (θ = 90), then

the force is given by F = BIL.

10. If there is also a magnetic field between two charged plates in

addition to the electric field, and the fields are crisscrossed, that allows the

charge to pass through undeflected, qE=F, and F=qvB , yields v = E/B.

11. Again, for regions where both electric and magnetic fields exist:

V=Ed, qE=F, and F=qvB. Manipulating these formulas allows you to write an

expression for the accelerating voltage in terms of v, B, and d.

12. When a conductor of length, L, and velocity, v, moves across a magnetic

field, B,  an Electromotive Force (Emf), ε, is induced in the conductor. This is

given by ε = BLv.

13. The current in the conductor is now given by I = ε / R, which is now Ohm's

Law for current from induced Emf.

14. The total magnetic flux through a plane area, A, placed in a uniform magnetic

field depends on the angle between the direction of the magnetic field and the

direction perpendicular to the surface area. The equation is Φ = BAcos(θ) .

15. Faraday discovered that when the magnetic flux, given by the Greek letter Phi,

Φ, changes with time, an electromotive force, or Emf, is produced. Or we can say,

21. And to get full credit for your homework make sure you are following

these steps

(i) read the problem and identify the given variables

(ii) determine what you are asked to solve for

(iii) find the correct formula to use

(iv) use algebra to isolate the unknown

(v) substitute-in the given information and simplify.

Answers to Homework: (Scrambled Format.)

THE HONORS PHYSICS ARCHIVES Ch.1: Physics Intro. Ch.2&3: Linear Motion. Ch.4&5: Forces. Ch.6: 2-Dim Motion. Ch.7: Gravitation. Ch.8: Rotary Motion. Ch.9: Momentum. Ch.10&11: Work&Energy. Ch.12: Thermal Energy. Ch.13: States of Matter. Semester Review. Ch.14&15: Waves&Sound. Ch.16: Study of Light. Ch.17&18: Mirrors & Lenses. Ch.19: Light Interference. Ch.20&21: Electrostatics. Ch.22&23: DC Circuits.