Due 4/23

OK - talked with Mr. Parsons. The book was wrong on Q 16 (p781). Think of A as being towards you. Since electrons are moving use the Left Hand Rule. Because it is moving in a circle and is an internal magnetic field use the LHR where you make a thumbs-up sign (Fonzy sign). It says the electrons are going clockwise, so put your fingers of your left hand clockwise. Your thumb should be pointing towards you. This means that the current makes a magnetic field (B) with the north pointing towards you, which is letter A. So, letter A is a north, which will point towards the earth's north pole, just like a compass.

Q 14 - my mistake. I forgot that the direction of B (magnetic field) shows the direction that a north pole would point. Ex. If B points south, a north pole of a magnet would point south at that place. So, Q 14 talks about electrons, so use the LHR. If the e's are flowing E to W, then they are going right to left in front of you (let's consider N to be going forward). Using the LHR, point your left thumb toward your left. That's the wire. Above the wire your fingers should be pointing towards you. That's the direction of B - towards you - South.

OK - homework.

1) Do these Regular Physics homeworks - Magnetism 2 (all of it), and Magnetism 3. (skip # 18). On Mag 3 - Q 16 should read: what is the shape of the path of a charge moving perpendicular in a uniform magnetic field. (I believe that is in the book.)

2) Answer these questions about a charge moving in a magnetic field: A. If the velocity of the particle doubles the force ___________; B. if the force increased by a factor of 3, the magnetic field changed by a factor of _________.

3) Quiz next time. Know the direction of magnetic fields; F = qvB (moving charge in a magnetic field); F = qIl (current carrying wire); about domains; about electromagnets; right-hand rule and left-hand rule. SO - do the website quizzes, remembering that those quizzes are only for positive charges, not negative charges. Read the chapter well and the quiz is easy.