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Making a Small Motor!

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Emma Khazzam!!

Académie de la Capitale!!

Mme Neena!!

11th grade, Physics!!

January 20th, 2014

The purpose of this experiment was to build a small direct current motor. Motors are used in many objects in our daily lives such as computers, fans, hand dryers, elevators, amusement park rides, and much more. !!!!Materials (figure 1)!• at least 2 large paper clips!• masking tape!• ceramic magnets!• coated, 16 gage copper wire!• sandpaper!• a C cell battery!• a pencil!!!!!!!!!!Procedure!!1. Take a pencil and insert it into one of the paper

clips. Twist the paper clip around so that it forms a circle as shown in figure 2. Bend the paper clip so that it resembles the paper clips in figure 3. Repeat with second paper clip.!!

!!!!!2. Tape the paper clips to a solid surface about one

and a half inches apart, as shown in figure 3. The battery must be able to fit in between the paper clips. This is the base of your motor.!!!!!

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Figure 3

Figure 2

Figure 1

!!3. Wrap the copper wire tightly around the battery

about 10 to 15 times (figure 4). Leave about two and a half inches of wire loose at each end. Gently slide the coil off the magnet, and compress the loops together.!!!!!!

4. Wrap the loose ends of the wire into and around the coil two to four times to secure the coil in place, as shown in figure 5.!!!!!!

!!!!!5. Remove ALL the coating off ONE end of the wire

using the sand paper, as shown in figure 6. IMPORTANT: On the other end of the wire, remove only HALF of the coating. (Figure 7) This is your rotor.!! ! !!

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Figure 4

Figure 5

Figure 6

Figure 7

6. Insert the ends of the wire through the paper clips as shown in figure 8. Make sure that the wires are straight and that the rotor can spin smoothly.!!!!!!

!!!!!!!7. Slide the magnets underneath the coil (figure 9).

Adjust the height of the magnets so that when the coil spins it just clears the magnets but does not touch them, about 2mm.!!!!!

!!!!!!8. Place the battery in between the other ends of

the paperclips and touch them to the poles of the battery as shown in figure 10. Give the coil a small spin to start the motor turning.!!!!!

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Figure 8

Figure 9

Figure 10

Observations!!How does the motor work? The basic principle behind the simple DC motor is that current-carrying wires experience force when placed in regions that have a magnetic field. There are three key elements in a motor; a magnetic field, a current source and a wire. When a wire carrying an electric current is placed in a magnetic field, it will experience a force. The direction of the force can be determined with the right hand rule for the motor principal (figure 11). The right hand rule for the motor principal states that when the fingers of the right hand point in the direction of the magnetic field and the thumb, pointing perpendicularly to the fingers, points in the direction of the current, the palm will point in the direction of the force. If the current-carrying wire is bent in a loop, the two sides of the loop will experience forces in opposite directions. The forces cause a torque, a rotational force, which rotates the coil. When the upper part of the loop spins or rotates downwards, the forces switch, causing the coil to spin. An important factor in making the motor spin, is leaving one side of the end wire coated while the rest of the wire is uncoated. If all of the end wire were to be uncoated, the rotor would oscillate back and forth, 180 degrees one way, then back 180 degrees the other way. The rotor would never make a single complete rotation. When one side of one end wire remains coated, the current is cut off for a small fraction of time. When the current is cut off, the forces acting upon the coil stop, causing the inertia from the spin to complete the turn. This repeats itself over and over again causing the rotor to spin.!!!!!

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Figure 11

After the initial spin the rotor will continue spinning using energy from the battery. The electrical energy from the battery is transformed into the mechanical energy of rotation of the rotor. There are three factors that determine how fast the motor will spin; the amount of current derived from the battery that is in the wire, the strength of the magnetic field from the magnets, and the length of the wire. These three factors determine the size of the force. One loop of wire would have a certain amount of force and two loops of wire would be two times that about of force. The number of loops can significantly increase the speed of the motor, but, at some point, it can be detrimental to the speed of the motor. If one hundred coils were used for the small motor experiment above, the coils would have too much mass, and the magnets would not be strong enough to spin the motor. The materials used in the experiment have to be carefully calculated for motor to work properly.!!!!Conclusions and Improvements!!When I started working on the motor, I went through multiple designs. Figure 12 and figure 13 are some examples of templates that I tried when doing this experiment. After several days of trouble shooting I exchanged non-coated wire for coated wire and the experiment worked. The experiment taught me that when conducting an investigation it might take several attempts to achieve success. I learned that with a few simple materials I can build a functional motor.! !!!!!!!!!!!!

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Figure 13Figure 12

!Bibliography: !!R, Nave. "How Does an Electric Motor Work?." . N.p.. Web. 19 Jan 2014. <http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/mothow.html>.!!Beauvais, Kristy. "The Simple DC Motor:." . Massachusetts Institute of Technology, n.d. Web. 19 Jan 2014. <http://web.mit.edu/cmse/educational/motor_lp_kristy.pdf>.!!Physics 11 University Preparation. Toronto, Canada: Nelson Education Ltd., 2011. Print.