By: Metacafe Affiliate U
For the HSC Physics syllabus dot-points: “Perform a first-hand investigation to demonstrate the motor effect”, “Perform an investigation to model the generation of an electric current by moving a magnet in a coil or a coil near a magnet”, “Plan, choose equipment or resources for, and perform a first-hand investigation to predict and verify the effect on a generated electric current when: the distance between the coil and magnet is varied, the strength of the magnet is varied, the relative motion between the coil and the magnet is varied”, and “Plan, choose equipment or resources for, and perform a first-hand investigation to demonstrate the production of an alternating current”.
For the first dot-point, we wound wires five times, threading each loop through the region between two strong permanent (neodymium) magnets. We then applied a current of 3 amps through the wire (our power supply was auto current-limiting so no excessive heat was produced). With 5 loops threaded, each with 3 amps, the total effective current was 3x5 = 15amps, and a movement of the wires were observed. The direction of force on the wire was as predicted by the right-hand push rule (aka right-hand palm rule).
For the second dot-point, we tested each condition (distance, strength and speed of magnet) on a coil connected to an ammeter and we observed a direct correlation between strength of magnet and induced current, a direct correlation between speed of magnet and induced current, and an inverse correlation between distance of magnet and induced current.
For the final dot-point, we moved a magnet in and out of a coil connected to an ammeter. The ammeter needle’s direction of movement continually reversed, indicating that an alternating current was produced. We also used a hand-wound AC generator to power an incandescent light bulb.