Conceptual Physics Labs – Chapters 16 & 17

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Name _______________________________

Where appropriate – ALWAYS show your formulas and your work!

Use the back of your paper if you need to.

Making a Motor

Bend 2 paperclips as you see in Fig.1 Fasten them with rubber bands so they contact the positive

and negative terminals of the battery. Use a small piece of clay as a base so the battery doesn’t roll. Use a tiny piece of clay to stick a magnet to the top of the

battery. This is your motor base

Using about a meter of wire, create a ‘square’ form about 4 cm on each side, with about 4 cm of wire extending on each side.

Using sandpaper, remove the insulation completely on one side and on only one side of the wire on the other end.

Place the coil in the paperclip holders Adjust the height and balance until you can get the wire

‘motor’ to spin. When electricity runs through the coil of wire, what type of force is created around the coil? What is the purpose of the permanent magnet? Try adding a second magnet. Does this make the motor go faster, slower, or about the same?

Fig. 1

Fig. 2

Fig. 3

Conceptual Physics Labs – Chapters 16 & 17

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Transformers A family from Finland, where standard household voltage is 220 volts, is planning a trip to Japan. The transformer they need to use their appliances in Japan has an input coil with 250 turns and an output coil with 550 turns. What is the standard household voltage in Japan? An engineer in India (standard household voltage = 220 volts) is designing a transformer for use on her upcoming trip to Canada (standard household voltage = 120 volts). If her input coil is 240 turns, how many turns should her output coil have? Electric Fields What is the force of an electric field of strength 4.0 N/C on a charge of 0.5C? If an object with a charge of 0.08C experiences an electric force of 5.0N, what is the electric field strength? Be sure to show your work.

Conceptual Physics Labs – Chapters 16 & 17

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Mapping Electric Fields Using the computer SIM program found at http://phet.colorado.edu/sims/charges-and-fields/charges-and-fields_en.html, do the following:

Drop a positive charge into the middle of the field. Select one of the E-field sensors. The sensor is a test charge that feels the force of the

positive force you just dropped in the middle of the field. Move the E-field sensor around to test the charge

What happens to the length of the vector as you move the sensor closer to the positive charge? Is the sensor positive or negative? What tells you that? Now, place three charges on the screen and check the “Show E-field” box to display the field. Space out the charges so that you can see the forces between them. Draw and label your field and charges here. (You can draw continuous lines rather than lots of separate arrows.)

Conceptual Physics Labs – Chapters 16 & 17

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Van de Graaf Using the Van de Graaf generator, tape a disposable pie pan (like a hat), then stack another pie pan on top of it (not taped down). Start the generator and watch what happens to the second pie pan. It will take a few minutes. Tell what happened and WHY. Mapping Magnetic Fields Using the grid on the next page, set it on top of the provided tray. There is a magnet hidden underneath. Move the compass around on the grid and mark which way it points at multiple points around the page. Using this information, try to determine where the magnet is located. (See the sample below)

Conceptual Physics Labs – Chapters 16 & 17

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