Fall 2001
Today's Lecture (10/3):Summary:
- Magnetic fields are very similar to electric fields with one major difference, namely, there are no magnetic charges. Instead we only have magnetic dipoles. A familiar example of a magnetic dipole might be a compass needle. Magnetic fields determine the forces on a magnetic dipole in exactly the same way as electric fields determine the forces on electric dipoles.
- Magnetic fields also have an effect on moving particles that are electrically charged via the Lorentz Force Law.
The velocity and magnetic field vectors in this formula are multiplied using something called the cross-product.
- When two vectors, A and B, are crossed, the resulting vector has a magnitude determined by the magnitude of each vector and the angle between them.
The direction is perpendicular to the original vectors and the sign is given by the right hand rule. To apply this rule to the Lorentz Force Law, you should:
1) Point fingers in direction of v.
2) Curl them toward B.
Then your thumb points in direction of F.Conceptests:
Assignments:Next Reading Assignment (due 10/5)
Next Homework (due 10/10)
Diversion-of-the-week:This week's diversion is a "Rubik's cube"-like puzzle called Alien Tiles. I haven't gotten very far with it, but I'm hoping to sit down sometime and work out a better solution than the trivial one.
Let me know if you get better than 49 moves!
Please contact the WebEditor with site-related questions.
