An Attractive Tuesday

Honors Physics reviewed over the basics of electromagnetism and then stepped into electromagnetic induction. Magnetic flux can generate electric current and the value of that current is dependent on conditions of the flux such as change in field strength, number of windings present, speed of the fluctuation, etc. Induction was demonstrated by a solenoid hooked up to a galvanomenter. A bar magnet inserted into the solenoid core produced an electric current that was registered on the galvanometer. Inserting the magnet produced a current with a direction opposite that produced when the magnet was removed. Also, each pole of the magnet caused current flow in different directions. When the magnet was held stationary in the solenoid, there was no current generated. Without a change in the magnetic field, there is no generation of current. The Lenz’s law demonstration also showed the generation of current when a magnetic sphere was dropped into a copper pipe. The magnet fell at a rate substantially slower than that of a standard steel ball bearing. Lenz’s Law predicts that the current generated will produce a magnetic field that will oppose the flux in the external magnetic field and this demo is good for demonstrating that effect. Tomorrow, we pick up with generators!

Physical Science B began a discussion of electromagnetism today and had a few demonstrations thrown in, to boot. Students explored the magnetic fields produced by moving charges and how the magnitude of the magnetic field can be boosted by coiling and then winding the current-carrying wire. An air-core solenoid was demonstrated in class and compasses were used to document the pattern of the magnetic field lines. When the polarity was flipped, so did the directions the compasses pointed. An iron-core solenoid (electromagnet) was also demonstrated and its magnetic field strength was compared with that of the air-core solenoid. Tomorrow, we begin to look at devices that rely on electromagnetism, such as motors.

Physical Science E began their classroom discussion of permanent magnet and magnetic fields today. Armed with information from yesterday’s film, students were able to work through the nature of magnetism and the properties of permanent magnets, magnetic fields and field lines and characteristics of Earth’s magnetic field. Tomorrow, we explore the ability of moving charges to generate magnetic fields.

Physics F picked up with magnetic forces today and discussed the behavior of charged particles and current-carrying wires in magnetic fields. The right-hand rule was implemented to determine the direction of the forces produced and factors affecting magnetic force – particle charge, velocity, magnetic field strength and angle of travel – were described. The structure and function of the galvanometer was investigated and time was given for folks to work practice problems with magnetic forces.

Physics G began discussing the ability of moving charged particles to produce magnetic fields. The magnetic field of a straight wire, a coil and a solenoid was described and the ability of an iron core to increase the field strength of a solenoid was investigated and demonstrated. Charged particle motion was then linked to magnetic domains in permanent magnets. Tomorrow – magnetic forces!

Homework

Honors Physics A: Practice 22A and the 22.1 Section Review
Physical Science B: 17.2 Section Review
Physical Science E: None
Physics F: Practice 21A #2,5; Practice 21B #3,4; Chapter Review #19-24, 26
Physics G: 21.3 Section Review