Build A Simple Electric Motor (example #1)

Transcription

1 PHY115 Experiment 11 Build A Simple Electric Motor (example #1) MATERIAL This is the necessary equipment. Present any list of material in your written lab report. 1.5 V battery in series 1 ceramic magnet cm long magnet wire 2 large paper clips 2 shelf clips sandpaper PRELIMINARY QUESTION Is the magnet provided a conductor of electricity? Test it and answer this question in your report. PROCEDURE Wrap the wire around a pen (or other cylindrical object, from 1 to 4 cm in diameter, you choose). Now wrap the ends back around the coil. This will both support the coil and create the axle for your motor. This is the most challenging part of the experiment.

2 It is critical that the axles balance the coil. That is, they must be almost exactly opposite one another on the circle of wire. Now use a piece of sandpaper to remove the enamel from the bottom of the wire on both sides. It is very important that you remove ALL the paint out of ONLY the bottom of the wire. Now it is assembly time! Look at the picture below. You are welcome to do any modifications you find appropriate! Add the paper clips: the magnet holds it all together. Again, you are welcome to do any modifications you find appropriate! That s it. Is your motor spinning????

3 Build A Simple Electric Motor (example #2) MATERIAL This is the necessary equipment. Present this list in your written lab report. two 1.5 V batteries and battery holders (connect batteries in series) small magnets 60 cm long magnet wire 2 large paper clips 1 plastic cup masking tape electrical wires with alligator clips at both ends sandpaper, if you are using enameled copper wire wite-out, if you are using insulated copper wire PRELIMINARY QUESTION Is the magnet provided a conductor of electricity? Test it and answer the question in your lab report. PROCEDURE Wrap the wire around the battery (or other cylindrical object of about 3 to 4 cm in diameter).

4 Now wrap the ends back around the coil. This will both support the coil and create the axle for your motor. This is the most challenging part of the experiment. It is critical that the axles balance the coil. That is, they must be almost exactly opposite one another on the circle of wire. Now if you are using enameled copper wire, use a piece of sandpaper to remove the enamel from the bottom of the wire on both sides. It is very important that you remove ALL the enamel out of ONLY the BOTTOM of the wire. In case you are using insulated copper wire, then after the insulation is stripped off at the ends, apply some wite-out to the top half of the write. Note: It is very important that the orientation of the wite-out painted side corresponds to the orientation shown in the figure below (the TOP half part needs to be painted). Now it is assembly time! Look at the pictures presented before. You are always welcome to do any modifications you find appropriate! That s it. Is your motor spinning????

5 REPORT In your lab report, follow the usual structure: COVER PAGE, PURPOSE of experiment, DIAGRAM of experiment and add to it the LIST OF MATERIALS used. Next, you will write an ANALYSIS section explaining the physical concepts behind the functioning of this simple electric motor. This is the most important part of your report, this is the part that needs to show clearly that you understand the physics involved in this experiment. 60% of the grade for this report will come from the analysis section. Do not copy this section from each other. Points will be taken out if you: 1) copy from each other; 2 ) are not sufficiently clear about the physical principles involved ; 3) are not complete in your description. Your source of reference can be textbooks, the class slides that are online, and the internet. I expect you to write several paragraphs describing the following physical concepts. Write about electric circuits: Where is the electric circuit in the motor? Describe the path followed by the charges. Where are V and I coming from? Is there any resistance R in this circuit? Where? Is it important? Write about loops and electromagnets. You can use equations in your report if you prefer. What is the relation between electric current and magnetic field? What happens when electric current flows through a looped wire? How does a solenoid works? What is electromagnetic INDUCTION? Does a CHANGE in electric current induces a magnetic field? Does a CHANGE in magnetic field induces an electric current? In the CONCLUSION section (final section of your report), answer the following questions. Each question is worth 0.5 points. 1. Once current flows through the coil, does it become a magnet? Where are the poles in the coil? 2. How will the coil interact with the permanent magnet underneath it? (Remember that magnets have poles.) 3. So, what makes the coil spin? Or in other words, what will produce the force necessary to start the coil spin? 4. You have stripped the insulation off only one half of the wire (or used wite-out to insulate a side). What happens with the flow of electric charges in the coil and the magnetic field in the coil when the insulated part of the wire touches the clip or holder? Do they turn off? 5. What would happen if you hadn t stripped the insulation off one side of the wire? Would the coil keep spinning by itself? Why / why not? 6. Let s suppose now that you unplug the battery from your motor, and connect an ammeter in its place the ammeter is there only to measure current, not to provide power. Next you spin the coil with your hand. Will the ammeter register anything? Would you generate electricity?