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SCRIPT FORM - TR 130 – (for a 5 minute show) Producer: Jerome Ferro Show Title: The Science Fair. Date: 09/29/2015 Time Video Audio 6:00 Bars Tone 5:30 Slate 5:10 Countdown 5:00 Camera With tone Show Title super (key over opening shot) Lower 3rd super: host .What do elevators, escalators and subway trains have in common? They all contain electric motors. Electric motors are an important, and even vital, part of our world today. But, you may have wondered, just how do electric motors work? Hi, I amJerry Ferro, during these next few minutes I will demonstrate how to build a simple electric motor and explain the theory of operation. I will build a simple electric motor, called a Beakman's motor. Have you ever played with magnets? If so, you are well on your way to understanding how simple electric motors work. Magnets produce a magnetic field with a north pole and a south pole. If you try to point the north poles of two magnets together, they will not want to come together. Instead, they will repel each other. The same thing happens if you try to point two south poles together. If, however, you bring the north pole of one magnet close to the south pole of another, they will attract each other and stick together. Like poles repel, opposite poles attract. The stronger the magnets, the more forceful the attraction / repulsion is between them. Magnets are typically black, so there is no visible way to tell which end is north and which is south. You can detect a magnetic field and determine the north/south pole with a compass. As opposite poles attract, the north pole of the needle will be attracted to the south pole of the magnet. This method of determining the poles of a magnet can also be used to detect the presence and direction of a magnetic field around an electromagnet. An electric motor uses the attracting and repelling properties of magnets to create motion. An electric motor contains two magnets; in this project, I will use a permanent magnet and a temporary magnet. The temporary magnet is also called an electromagnet. A permanent magnet is surrounded by a magnetic field all the time, but the electromagnet creates a magnetic field only when electric current is flowing through a wire The strength of the electromagnet's magnetic field can be intensified by increasing the current through the wire, or by forming the wire into multiple loops or wraps. Such loops of electrical wire are often called a coil. To make an electric motor, the electromagnet is placed on an axle so it can spin freely. It is then positioned within the magnetic field of a permanent magnet. This is when things get interesting! When a current is passed through the electromagnet, the resulting magnetic field interacts with the permanent magnetic field to create attractive and repelling forces. These forces push the electromagnet, which freely spins on its axle, and an electric motor is born. The strength of the permanent magnet and the electromagnet will play a role in the strength of the repelling or attracting forces, and this effects the speed at which the motor is spinning. The electromagnet is a coil. Because all loops of wire are parallel, each loop will get the same push. Adding up all those pushes, or motions, creates the nice spinning movement of a motor. There are actually several ways to make the electromagnet placed in a permanent magnetic field spin. The solution applied in this project uses Newton's first law of motion , which states that an object in motion remains in motion unless acted upon by an outside force. This means that when the electromagnet is spinning, it will continue to coast through a rotation unless something stops it. As discussed earlier, if current is always flowing through the wire, the resulting pushes will oppose each other, and the coil will bounce back and forth, but not spin continuously. However, if we can make the current flow only half of the time, all the pushes are in the same direction. This means the coil is actively pushed one-half of each rotation while current is flowing, and "coasts" through the next half while no current is flowing, until it comes around and receives the next push. This allows the motor to spin continuously. This project will demonstrate the process of creating a simple electric motor. I will start by creating an electromagnet suitable for the motor. The electromagnet will then be placed in a permanent magnetic field and then we will see what happens! Key CG Materials Materials: These specialty items can be purchased from the Science Buddies Store: Electric Motor and Generator kit (1). You will need these items from the kit: Magnet wire, enamel-coated, approximately 50 inches [120 cm]. This quantity allows for recoiling a second coil if needed. Jumbo paper clips (2), metallic, 1½–2 inches [2.6 cm] long Sandpaper, fine-grit Neodymium magnets (3), 1/4 inch [0.6 cm] diameter Compass (1) Note:The kit also contains enough pieces to do two additional electricity projects. A dowel or other cylinder, 1/2 inch [1.3 cm] in diameter. Ruler or measuring tape Scissors Piece of cardboard, 2 x 3 inches [5 x 8 cm] Battery, AA cell (2); though you may only use one, it's a good idea to have a second one on hand, as it is likely you will drain the first while tinkering. Tape (electrical tape or masking tape works best) I will build a simple electric motor, called a Beakman's motor. I will change the configuration and study its effect on the motor. From one end of the magnetic wire, measure about 1.6 inches (4 cm), and from that point onward, wind about 30 inches of magnetic wire around the cylinder . Cut the magnetic wire with the scissors, leaving about 1.6 inches (4 cm) free (uncoiled) at the other end. Key CG Figure1 The magnetic wire must be neatly and evenly coiled. If it is not, the weight may not be evenly distributed, making it difficult for the electromagnet coil to rotate in the final motor setup. Try to ensure the loops are touching each other, always parallel to one Key CG Figure2 another, as shown in Figure 1.A coil is formed by winding magnetic wire 30" neatly around a cylinder. Note 1.6 inches (4 cm) of wire is left free on each end to create the axles. Carefully slide the loops of magnetic wire off the cylinder. Your coil might look circular or square, as shown in Figure 2. In this graphic you can see two examples of neatly coiled wire, each creating an electromagnet. Key CG Figure3 Keep the loops bunched together to form a tight coil: Thread each free end of the magnetic wire through the loops of coil in the 3 o'clock and 9 o'clock positions, as shown in Figure 3. If desired, you can knot the magnetic wire to help the coils stay tightly bunched. The free ends of the magnetic wire should form a straight imaginary line through the coil (the imaginary line connects the 3 o'clock and 9 o'clock positions and runs further along the free ends). The free ends will be the axle on which your electromagnet spins. Figure 3 is a drawing showing how the coil and the axle that it spins on look when formed. Note how the two axles lie in an imaginary straight line across the middle of the coil. The magnetic wire is protected with electrically insulating enamel coating. This electrical insulation needs to be removed from the ends of the axles to create electrical contact between the left axle and the right axle support. It is important to be thorough about stripping off the insulation. To strip only the top half of the insulation off the end of a wire : Lay one end of the wire on a piece of cardboard (to protect the table underneath) at the edge of a table or counter. Hold the other end of the wire in your hand. Rub the sandpaper over the wire to remove the top half of the insulating material from the magnetic wire. The insulating coating is removed when you can see the copper wire underneath. To strip all the insulation from the opposite end of the wire : Fold the piece of sandpaper in half, with the rough sides facing each other, to make a "sandpaper sandwich." Put the end of the magnet wire that you want to strip inside the sandpaper sandwich. While softly pressing the sandpaper sandwich together, gently rub it over the wire, back and forth. Give the wire a quarter turn and rub some more to remove the coating on all sides of the wire. The wire is stripped when you can see the copper wire underneath. Be careful not to press too hard when rubbing or the wire could break. Note : Only the end of the axle needs coating to be removed. The first centimeter (3/8 inch) of the axle (closest to the coil) does not need to be sanded. Do try to remove all the coating on the top side of the wire. You should be able to see the bare copper wire. Key CG Figure4 Flip the coil around and sand the end of the left axle. On this side (the left axle), remove all the coating, as shown in Figure 4. Note: This step is important as well, so try to be accurate. The top part of this drawing shows how the axles should be stripped: on the right axle, only the top half of the coating should be removed; on the left axle, all the coating should be removed. Technical Note Why do we strip the wire this way? Remember that stripping the insulation allows electrical contact so electrical current will flow. Stripping off the top half of the insulating material on the right axle will provide a period of time when current can flow through the coil to create a temporary magnetic field and a period of time when current cannot flow, so no temporary magnetic field is created. When the bare copper of the axle is rotated downward, bare copper will be touching the axle supports, and current will flow to the coil. As soon as current flows through the coil, it becomes an electromagnet, creating a temporary magnetic field. The temporary magnetic field will interact with the permanent magnetic field and give the wire a push. When the bare copper is rotated upward, insulated copper will be touching the axle supports, and no current will flow to the coil. There will not be a temporary magnetic field. According to Newton's first law of motion, the coil will keep moving the way it moved before, because no force is stopping it. As soon as the bare copper of the axle is rotated down again, current will flow and the coil will get a new push, making it rotate around and around. So far, I have built the electromagnet. Now I will attach the coil to the base constructed off camera so that current can flow through the coil. I have modified the next part of the motor, because it is easier to work with than taping paperclips to a C battery. I used 2 solder type terminal strips to form the loop of the axle supports for the electro-magnet to be suspended on and soldered the plus and minus of a battery holder leads to the base of the center terminals on both ends. Insert each axle end into a loop of the axle support. The motor might well start running right away! This motor needs some fine-tuning: Adjust the axle supports so the axle is horizontal. Give the coil a few turns to make sure it can spin freely and does not rub against the magnet. Turn your coil 180 degrees, as maybe the uncoated side of the axle was facing up, not touching the axle support. Contact of the bare wire with the axle support will create an electrical connection and allow current to flow. CAM Key CG Credits SOC (standard out cue) Theme Music Fade to Black Fade out Music