v+alva


 * Topic:**

**Problem:**
To learn how to build a simple electric motor and to determine which motor design produces the fastest rate of spin.

**Materials:**

 * Measuring tape or ruler
 * Battery (AAA size) or ballpoint pen
 * Knife
 * Magnet wire, enamel-coated, 22-gauge (or thicker), Radio Shack part # 278-1345
 * Piece of cardboard, about the size of a piece of paper
 * Wire cutters
 * Bare copper or brass wire, 18- or 20-gauge, Radio Shack part # 278-1217 or # 278-1216, or 6 straightened paper clips
 * Nail, small
 * Battery holders, Radio Shack part # 270-402 (holds a "C" cell) or # 270-403 (holds a "D" cell) (3)
 * Batteries to fit the holder, C or D cell, depending on your battery holders (3)
 * Strip of paper (3)
 * Magnet, Radio Shack part # 64-1877, # 64-1895, # 64-1883, # 64-1879, or # 64-1888 (3)
 * Voltmeter
 * Lab notebook
 * Poster board

**Procedure:**
You will be building and comparing three simple electric motors, called **Beakman motors**. The first motor will have 10 coil windings, the second will have 30 coil windings, and the third will have 50 coil windings.

Building Your Electromagnet

 * 1) Measure out about 2 inches of magnet wire, and from that point on, begin winding your magnet wire 10 times around the AAA battery or ballpoint pen. Cut the wire with the wire cutters, leaving about 2 inches free (uncoiled) at each end.
 * 2) Carefully slide the loops of wire off the AAA battery or ballpoint pen.
 * 3) Now you need to wrap the loops so that they stay bunched together and form a tight coil. Wrap each free end of wire around the loops of coil two times in the 3 o'clock and 9 o'clock positions, as shown in Figure 3. If desired, you can then knot the wire to help the coils stay tightly bunched. The free ends of the magnet wire should form a straight line through the coil. The free ends will be the axle upon which your electromagnet (the loops of wire) spins.


 * [[image:http://www.sciencebuddies.org/science-fair-projects/project_ideas/Elec_img134.jpg width="577" height="261" caption="This drawing shows circular loops of wire with knots and axles in the 3 o'clock and 9 o'clock position where the loops are bound."]] ||
 * **Figure 3.** This drawing shows how the electromagnet and the axle that it spins on will look when it is formed. ||
 * 1) Using a sharp knife, strip off the **insulating** material on //half// of the axles, as shown in Figure 4. The easiest way to do this is to hold the coil between your thumb and forefinger so it is standing upright (the coil is perpendicular to the floor) and then hold the coil off to one side of a table. (If you want to see an image of how to hold the coil, view the sixth figure in these [|assembly instructions for a Beakman motor].) Lay the axle on a piece of cardboard (to protect the table underneath) and scrape off the top half of the wire with a knife. Be careful not to press too hard when you are scraping or you might cut the wire or cut into the table. Flip the coil around and then scrape the other axle. Scraping off half of the insulating material is done to provide a period of time when current can flow through the coil and create a temporary magnetic field, and a period of time when it cannot. When the bare copper of the axle is rotated down, bare copper will be touching the axle supports, and current will flow to the coil, creating a temporary magnetic field. When the bare copper is rotated up, insulated copper will be touching the axle supports, and no current will flow to the coil.


 * [[image:http://www.sciencebuddies.org/science-fair-projects/project_ideas/Elec_img135.jpg width="500" height="249" caption="This shows a circular coil with axles extending from it in the 3 o'clock and 9 o'clock positions. The top half of the axles are stripped of insulating material exposing the bare copper beneath."]] ||
 * **Figure 4.** This drawing shows the parts of the axles to strip of insulating material. ||

Building Your Axle Support

 * 1) With the wire cutters, cut two equal lengths of stiff, bare copper or brass wire, approximately 3-4 inches long. Two straightened paper clips are also possible alternatives.
 * 2) Bend each wire around a small nail to form a loop. Slip the wires off the nail. Now each axle support should look like the end of a safety pin. Each one should look like a loop with two legs.

Building Your Electric Motor Base

 * 1) The battery holder makes a good electric motor base because it is heavy and stabilizes the electromagnet as it spins. Wind the free ends of your axle supports (the two legs) into the holes in the plastic at each end of the battery holder, as shown in Figure 5.

Building Your Electric Motor

 * 1) Insert each axle into an axle support. Adjust the axle supports so that they are close to the coil, but not touching it.
 * 2) Place the magnet on top of the battery holder, below the coil. Give the coil a few turns to makes sure it can spin freely and does not rub against the magnet.
 * 3) Place the battery and a strip of paper inside the battery holder. The strip of paper is the on/off switch. When the paper is in place, it acts as an insulator and prevents current from flowing (the switch is off). When you pull out the paper, current can flow. It is like turning the switch on. Your finished electric motor should appear similar to the setup shown in Figure 5.


 * [[image:http://www.sciencebuddies.org/science-fair-projects/project_ideas/Elec_img136.jpg height="479" caption="Diagram of a Beakman motor"]] ||
 * **Figure 5.** This drawing shows how to connect the electromagnet and its axles, the permanent magnet, axle supports, battery, and its paper switch to form a simple electric motor. ||
 * 1) Repeat the steps Building Your Electromagnet through step 3 of Building Your Electric Motor, replacing the 10 windings with 30 windings, to form your second electric motor.
 * 2) Repeat the steps Building Your Electromagnet through step 3 of Building Your Electric Motor, replacing the 10 windings with 50 windings, to form your third electric motor.

Testing Your Electric Motors

 * 1) Use Fleming's Left Hand Rule for Motors to predict which way the motor should spin.
 * 2) Remove the strip of paper from your first motor. The electromagnet should start to spin on its axles. If it does not, consult the Bibliography for troubleshooting tips. Write down the direction of spin in your lab notebook. Just for fun, flip the magnet over. What direction does the motor spin now? Does this agree with Fleming's Left Hand Rule for Motors?
 * 3) Use the voltmeter to measure the voltage across the axle supports and record your measurement in a data table, like the one below, in your lab notebook.
 * 4) Measuring the speed of the motor (in revolutions per minute [rpm]) is difficult without specialized equipment, such as a voltage probe or an oscilloscope, but visually inspect your motor and describe whether it is spinning at a slow, medium, or fast rate of speed. Record your observation in your data table.
 * 5) Replace the strip of paper to stop the motor from spinning.

**Trial 1 Data Table**
 * Electric Motor Windings || Voltage Across Axle Supports (V) || Speed of Motor (slow, medium, fast) ||
 * 10 ||  ||   ||
 * 30 ||  ||   ||
 * 50 ||  ||   ||
 * 1) Repeat steps 2-5 of Testing Your Electric Motors for the other two motors.
 * 2) Repeat steps 2-6 of Testing Your Electric Motors two more times for each motor, for a total of three trials each. Record your data in two additional data tables.
 * 3) Average and record the voltages for each motor from each of the data tables.

**Average Voltage Data Table**
 * Electric Motor Windings || Average Voltage Across Axle Supports (V) ||
 * 10 ||  ||
 * 30 ||  ||
 * 50 ||  ||
 * 1) Which motor spun the fastest? Which motor spun the slowest? Was the average voltage lower for the fastest spinner?

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TOPIC

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=﻿II Materials:=

=﻿III. Procedure:=

=﻿IV. Hypothesis=

=﻿V. Data=

=﻿VI. Conclusion=

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