Student "edition" found at {csi dot journalspace dot com}.

Maybe I shouldn't have started this blog now, not with everything that's been going on.

In my Introduction to Electricity and Magnetism class on the fourth day of the twelfth week of the first term, just like in my Differential Equations class preceding, I took up the last topic for the term, which is magnetic fields.

I gave the equation for getting the magnetic force felt by a particle with a velocity in a magnetic field. This, as given by the cross product, is perpendicular to both initial directions.

Same with the torque of a coil in a magnetic field, given the dipole moment - which is equal to the product of the number of turns, the current and area of the coil – and the magnetic field. The direction of the dipole moment is also determined by the right hand rule.

The magnetic potential energy is given as the negative scalar (not a vector like the previous two) of the dot product of the dipole moment and the magnetic field.

The magnetic force on a current carrying wire is again the cross product of the current and the magnetic field.

As for magnetic field produced by a long straight wire, it is equal to the permeability constant (mu sub zero) times the current divided by two times pi times the distance from the wire.

Magnetic field from a circular arc at the center is half the value above, multiplied by the angle distended by the arc in radian measure. This allowed for the pi in the denominator to be cancelled out.

The magnetic field of a wire coil is just dependent on the current and the number of coils, both multiplied to mu sub zero.

Lastly, the force between two parallel current carrying wires is equal to the magnetic field of one at the distance of the second, multiplied by the second current and the length of the wire.

I gave them checkpoint exercises afterwards, which they finished by group.

On the next day, my Mathematical Methods One class had their last quiz, the coverage being geometric sequences, binomial theorem and the definition of logarithms.

One student was late again (consistently) despite just staying in the student dorm. There were also more students from the second and third tier who finished first, before those from the last (and best) row of scorers. And there were at least a dozen again that were still answering during the last fifteen minutes.

Session 714 passes its paper here. Class dismissed.