Now connect the alligator clips so that they use just one battery. How do you think that will change the scale’s reading? Now reverse the direction of the current in the straight wire by swapping the ends of the alligator clip leads that touch the positive and negative sides of the battery. Does the reading on the scale change from zero? (Don’t keep the wire connected for longer than necessary to get the reading, as the connection is rapidly discharging the batteries in this and all the rest of the investigations.) Use the other alligator clip lead to connect the free end of the straight wire to the negative side of the batteries. Attach one end of an alligator clip lead to one side of the straight wire, and the other end to the positive side of the batteries. Hold the straight wire between the magnet faces, but not touching the magnets or the scale. Then tare the scale by setting it to read zero.īegin by using both batteries in series. Put the short end of the magnet assembly on the scale so it stands up vertically. Insert the batteries into the battery holder. When you’re done, set the wires aside.ġ0. Leave one wire straight, bend another wire into a tight U-shape, and bend the third wire into a zigzag, as shown in the photo below. Cover all but the ends of each wire with either shrink wrap or electrical tape (see photos below).ĩ. With wire cutters, cut the armature wire into three pieces, each about 1 foot (30 cm) long. When you’re done, set this assembly aside.Ĩ. Add the remaining nuts to hold everything in place. Set the second piece of plastic onto the assembly so the magnets face one another (see photo below). Repeat on the second screw (see photo below).ħ. Twist a nut down onto one of the screws so it’s approximately 1/2 inch (1.25 cm) from the nut at the base. The heads of the screws should be on the opposite side of the plastic from the magnet The threads should extend outward on the magnet side. Push the nylon screws all the way through the open holes on one piece of plastic. Be sure the exposed faces of the magnets will attract one another (see photos below).ĥ. Using flat-head machine screws and nuts, attach each magnet to a piece of plastic. Put on safety glasses, and drill all the holes with appropriate bits (see photo below), and then pull off the tape.Ĥ. Approximately one-quarter of the way from each end of the plastic, mark holes for the nylon screws on the plastic pieces. Set the magnet aside and go on to Step 3.ģ. Center one of the magnets on top of the taped plastic pieces, as shown in the photo below, and use a pencil or marker to note the position of the holes on the tape. (This will allow you to drill both pieces at once, so the holes will line up later.)Ģ. Place the two pieces of plastic one on top of the other and tape firmly together, as shown in the photo below. Optional: 10-amp multimeter and an additional alligator clip leadġ.Two alkaline D-cell batteries (do NOT use rechargeable batteries).Battery holder (either commercial or homemade is fine: we used nails pounded into wood).Electrical tape or heat-shrink tubing and heat source.Three feet (1 yard) of 1/8-inch (3-mm) 10-gauge aluminum armature wire.Electric drill and drill bits: 1/4-inch (6.35 mm) bit for the nylon thumb screws, and appropriate bit for the countersink.Two #1/4-20 nylon thumb screws, 1 3/4 inches (1.5 cm) long.Four flat-head machine screws and nuts to match the countersunk holes.Two rare-earth magnets, each 1 x 1 x 3/16 inches (2.5 x 2.5 x 0.5 cm), with dual countersunk holes (other sizes will work).Two sturdy pieces of plastic, each approximately 1 1/4 x 3 x 1/4 inches (Delrin or a similar material).
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