Experiment leads: Tommy Chen and Bernie Cook
Students and Science for All members explored concepts of electricity and magnetism through an introductory demonstration and a set of three group experiments. Tommy and Bernie introduced electricity and magnetism with a short presentation and an initial demonstration that showed the interplay between the two disciplines by using a copper tube and neodymium magnets. The copper tube was shown to not be inherently magnetic by touching the magnets to the tube and letting them drop, where students observe no forces between the two. However, it was demonstrated that dropping the magnets through the center of the tube resulted in the magnets to fall at a much slower pace. This was caused by induction of Eddy currents in the pipe from the magnet’s magnetic field moving through the tube – the induced currents in the pipe produce a magnetic field and force that opposes the direction of gravitational acceleration on the magnet, causing it fall more slowly. Electric trains and roller coaster brakes were related to the demonstration as applications of the phenomenon.
The class was then divided into three groups, each of which would rotate through three different experiment stations. In the first experiment, students created a potato battery to power an LED by inserting one copper and one zinc metal electrode into each potato to produce a galvanic cell and connecting the potatoes in various ways. This illustrated conversion of chemical to electrical energy and difference between parallel and series circuits. In the second station, students made an electromagnetic projectile device out of an open circuit consisting of two aluminum foil sheets attached to a 9V battery, which could be closed with a round, conductive metal cylinder. Upon closing the circuit with the cylinder, the cylinder would roll either towards or away from the battery (depending on the direction of current), showing students that a change in current will induce a magnetic field and force and cause the metal to roll. Additionally, a simple magnetic train was used to demonstrate a similar phenomenon wherein a battery with magnets attached to its ends was inserted into a coiled copper wire after which it traveled to the end of the wire without additional force. The last experiment station demonstrated how an electromagnetic induction motor, commonly used in items such as blenders or fans, functions. Students coiled magnetic copper wire, suspended it with a set of metal brackets to allow the coil to rotate, and completed a circuit by connecting a battery to the brackets. Then, a magnet was brought close to the coil, after which the coil began to rotate – this showed how continuous rotation could be achieved as the magnetic field produced by the magnetic copper wire circuit oscillated between opposing or not opposing the magnet.