Lab 23—Charge Lab

This is a great introductory lab that gets students to visualize charge. The materials you will need for the lab are simple and can be obtained easily if you do not have a premade kit. You will need straws, something to charge a straw with (such as a sweater or even hair!), an ample supply of scotch tape, Styrofoam cups, and paper pieces. A good option for that last part is to raid teacher work rooms and classrooms for hole-puncher leftovers!

There is little that is needed in terms of setting this lab up. It is very straight forward and the process for doing the lab is described in the write up itself.

Name: ________________________________Period: _____

Physical Science- Charge LabPart A: Electrical InteractionsMaterials: plastic straw, paper bits, Styrofoam coffee cup, wool (as in a wool sweater or wool blanket)

1. Tear part of a piece of paper into small bits. Take a plastic drinking straw and bring it close to the bits of paper. Can you lift the bits of paper by touching them with the straw? ___________  

2. Now rub the straw briskly with cotton or wool and try to lift the bits of paper from the table. Can the scraps of paper be lifted even if you do not allow the rubbed straw to touch them first? ___________  

Which of the three methods of charge transfer did you use?

3. Repeat this using the Styrofoam coffee cup, trying to lift the paper bits before and after rubbing the cup on wool, fur or your hair. What are your results with the cup?   Before rubbing: ________

After rubbing:_________

4. Draw a force diagram of the tiny bits of paper that are lifted up by the straw. Which force is stronger, gravity or the force of the electric attraction?

Part B: Interaction Between Charged and Uncharged ObjectsMaterials: Scotch magic tape, paper bits, sheet of paper.Obtain about 15 cm of the Scotch tape and make tabs by folding the first centimeter of tape on each end, sticky side together. Stick the tape to the table-top and press and rub it down well with your finger. Now peel the tape carefully but briskly from the table top.  

1. Use the scotch tape to try and pick up the scraps of paper. Will either or both sides of the tape attract the scraps of paper? Explain what you see.

Sticky Side: ______________ Smooth side: __________Observations:

2. Roll a piece of paper into a tube and bring it near the tape. Is there an interaction between the paper and the tape? What type of interaction (attractive or repulsive) is it?  

 3. Stick the tape on the end of the table so the “charged” part is hanging off. Bring your

finger near the tape, what happens?

Part C: Interaction Between Two Charged ObjectsMaterials: Scotch magic tape.

1. Make a second tape strip like the first one. Press them both down on the table separately, and then peel them loose from the table. Try bringing the tapes near each other.

The pieces of tape _____________ (attract, repel or no interaction) each other.

Based on you answer to the above blank make a guess about the charge of the two pieces of tape.

Tape 1: ________ (+/-)Tape 2: ________ (+/-)

Does it matter which sides of the tape face each other?

2. Make a third strip of tape, charge it and try bringing it close to each of the other two tapes. Compare one of yours with those of another student, or stick their ends to something so that you have enough hands. What do you observe?  Explain what you see by discussing the charge of the 3rd piece of tape.

    Part D: Do All Charged Objects Behave the Same Way?Materials: plastic straw, Scotch magic tape, Styrofoam cup.Tape a straw to the top of your desk or table so that about three-fourths of the straw sticks out over the floor.   Charge another 15-cm tape by sticking it to the table-top, rubbing the tape, and peeling the tape from the table. Hang this charged tape from the end of the straw by sticking the tape to the straw. This is a test tape.  

1. Make two new tape strips in the following manner. Label the first one A, press it down on the table, and rub it with your finger. Label the second one B, press it firmly down on top of A, and rub it with your finger. Peel the two-tape combination off the table. Bring them near the test tape. What do you observe?  

2. Carefully peel apart the two tapes. Hold one in each hand and bring them slowly towards each other. Explain what you see and guess at the charge of the tapes Observations: Tape A: ______ (+/-)

The pieces of tape _______________ (attract/repel/did nothing). Tape B: ______ (+/-)

3. Bring A towards the test tape. What do you observe (attraction, repulsion or no interaction)? Bring B toward the test tape. What do you observe (attraction, repulsion or no interaction)?

Tape A: ________________Tape B: _________________

4. Can Tape A pick up scraps of paper? Can Tape B pick up scraps of paper? Given the differences you have already seen, explain your results for this experiment.

Tape A: ________________Tape B: _________________

Lab 24—Voltage Lab

This lab is a good introduction to building circuits and using a voltmeter. This lab is best timed before doing any other circuit labs so that students can learn how to use the equipment. You need two light bulbs a group and two D batteries a group (any battery will work but D will last longest).

The lab is a step by step explanation of what to do and how to build the circuits. The only tricky part can be the wording: it asks for A-B, A-C, C-D, D-A voltages. These voltages refer to the location of the two probes for your voltmeter. The only other problem that occasionally comes up is occasionally attaching the two positive ends of the battery together.

Name: ______________________Period: ____

Physical Science—Voltage Lab

Questions:1. Does increasing the number of batteries increase or decrease the voltage2. Does increasing the number of light bulbs increase or decrease the voltage each light bulb

receives

Research and necessary equations: VOLTMETER (label the parts)

Hypothesis (answer the two above questions)

Procedure/Analysis:1) Obtain two batteries, two light bulbs, and a voltmeter.2) Measure the voltage of a single battery that has not been connected to a light bulb.

What does the volt meter read? ______________ (record it here)

Look on the battery and figure out how much voltage should be coming from the battery? _______________ (record it here)

Is that the exact amount you recorded above? Why or why not?

Connect the battery to light bulbs in the fashions described below:1) Connect one light bulb to one battery. Use the voltmeter to determine how much voltage on

light bulb is drawing. To do this, touch the voltmeter to the springs on either side of the light bulb. (If you do not see anything, try flipping around the voltmeter.

Voltage on one light bulb: _________________

2) Connect two light bulbs into the circuit by plugging one light bulb into another as seen below:

V

A B

On the above diagram, there are four letters representing where you should measure the voltages of the system. For example, for the first blank, you would connect the voltmeter to the spring denoted by point B and the spring denoted by point , and then write down the recording on the voltmeter below. A. Remember, if you voltmeter says zero, try switching the ends!

A-B voltage: ____________________

A-C voltage: ____________________

C-D voltage: ____________________

A-D voltage: ____________________

Analysis: How does the voltage each of the two bulbs individually draw (or take up) compare?

What is the difference in A-B and A-C? What does this tell us about the wire we used to connect B to C?

How does the difference between points A-D compare to the voltage drawn by just one light bulb?

3) Now connect two batteries together.CAUTION: make sure that you plug a negative terminal into a positive terminal. You will need to wrap the wires around each other. Wrap one red and one black together.

Measure the voltage difference of both of the batteries. What is it?

CD

Instead of using the first red socket (3V), try connecting the voltmeter to the middle red socket (10V). How was it different?

Once you have the two batteries together, connect a single light bulb to both of the batteries. Use the voltmeter to read the voltage across the single light bulb.

Voltage of one light bulb and two batteries: ___________

What is the difference between the voltage in the single battery system and the double battery system?

Which light look brighter, the single or double battery with one light?

4) Finally, connect two batteries and two light bulbs.

THERE IS PLACE TO RECORD DATA ON THE NEXT PAGE!

Measure the same voltages from before, but this time add an A-E:A-B voltage: ____________________

A-C voltage: ____________________

A B

CD

E

C-D voltage: ____________________

A-D voltage: ____________________

A-E voltage: ____________________

How does the voltage across each individual bulb change from the other time you had two bulbs in the circuit?

Compare the brightness of each bulb in the two batteries/ two bulbs setup to the brightness of the one battery/one bulb setup. (You may want to work with another lab group and have both setups running at the same time.)

What was the voltage reading for A-E? Why was it different then the voltage reading for A-D? What would you expect the reading to be from D-E?

What do you think would happen if you connected the batteries backwards (a positive end to a positive end)?

Conclusions:Write 2-4 sentences that discusses your answers to the questions.

Lab 25—Ohm’s Law Lab

The main take home message from Goal 4 is using Ohm’s Law. This lab goes about proving Ohm’s Law and lets students see it in action. The lab requires a voltmeter, ammeter, (or a multimeter) 9V battery, resistors, and lots of wires. The best option for resistors is visiting RadioShack and purchasing a supply of random resistors. You can get a big pack for fairly cheap. As for wire, it is easy to get a spool of wire and then attach alligator clips to make the circuits easier to build.

Building the circuit is the most difficult part of the lab for students. I suggest checking each lab group’s circuit before they start using resistors or meters. Once the circuit is built, students need to test one resistor at a time. Be sure to use values of resistors based on how sensitive your equipment is. If you are getting no currents, then use smaller resistors. If you are getting really high current, then use larger resistors.

Sample Items:1. Calculated the current. The unit would be amps.2. Graphs will vary.3. Slopes will vary4. As resistance increases, current decreases. (negative correlation)5.As long as the 2nd and 4th columns are the same, the data is consistent with Ohm’s Law

Name: ________________________Period: _____

Physical Science Lab—Ohm’s Law

PURPOSE: The purpose of this lab is to investigate the relationship between the three variables involved in Ohm's Law - Current, Voltage and Resistance.

SAFETY: Do If wires begin to feel hot, disconnect them immediately and let them cool. Do not build any circuit you were not directly told to build. CLOSE THE SWITCH WHEN YOU ARE NOT TAKING A READING! The circuit should not be connected for longer than 30 seconds… EVER!

THEORY:Ohm’s Law: I = V / R

PROCEDURE:

1. Gather a battery, a voltmeter, an ammeter, a resistor, and wire. Build the following circuit:

2. When your circuit has been constructed and approved by you teacher, you may close the switch and measure the voltage and the current. Use the 10V reference on your voltmeter. Record the resistance from the colored lines and the readings on both meters in your data table.

3. After you take the reading for one of your resistors, take the resistor out of your circuit while still leaving as much of your circuit in tact as possible.

4. Replace your resistor with another resistor, and repeat with your readings until you have completed the data table

V

A

DATA:After you have take the measurements for each of the first three columns, divide column three by column one to find column four.

ResistanceΩ

CurrentA

VoltageV

Voltage/ResistanceV/Ω

ANALYSIS: 1. What did we calculate by dividing the voltage by the resistance? What is the unit for this

column?

2. Graph current (dependent) versus resistance (independent).

3. Find the slope of your graph.

4. What is the trend seen in this data?

5. Is your data consistent with Ohm’s Law? Why or why not?

Lab 26— Renewable Voltage Lab

Although not the most informative lab, this lab is an effective lab for getting students excited about the possibilities of renewable energy and using circuits in the real world. The easiest option for solar panels is small project panels available from catalogs or at a RadioShack.

The lab is simple. To do it, attach the solar panel to a voltmeter. Then, using a protractor, hold the panel at the various angles, recording the voltage each time. The students will measure a full circle, every 30 degrees with solar panel. The data table is set up so that when they have turned the panel upside down, the angle they are measure is listed to the left. For example, when measure 210˚, students will actually be holding the solar panel at 30˚, but pointing the panel towards the ground. The other option is to use a full circle protractor which are harder to find.

Sample Items:1. Graphs will vary2. It should be a bell shaped curve based on how much sun the panel was getting.3. Use the equation P = V*I and plug in the voltage to find the power.4. Whatever the peak of the curve would be, that is the angle of the sun. It will vary based on when you do the lab. Also note, the peak will usually plateau out so it will be an estimate.5. It is important to make the notes so that the solar panel always provides the maximum available power to whatever source needs it.

Name: ______________________Period: ____

Physical Science— Renewable Voltage Lab

Purpose:To explore the methods of collection for solar energy

SAFETY PRECAUTIONS:Although this may seem obvious, DO NOT LOOK A THE SUN!!! Be careful not to short circuit the solar panel

Hypothesis:

Is holding the panel flat better, worse, or the same as holding the panel at an angle?

Procedure/Analysis:3) Obtain materials: two pieces of wire, a protractor, a solar panel, a heating lamp (if done

inside)4) Connect the solar panel to the voltmeter, paying special attention to positive to positive and

negative to negative5) Hold the solar panel upside down and even with the protractor.6) Tilt the solar panel up, 30 degrees at a time and record the voltage. By the time you are done,

you should do a complete circle. (NOTE: for the data points on the right, the protractor will be “upside down” and read the angle on the left)

Data:Angle Voltage Angle Voltage

0˚ --

30˚ 210˚

60˚ 240˚

90˚ 270˚

120˚ 300˚

150˚ 330˚

180˚ 360˚

Analysis:1. Create a graph of angle (your x axis) and voltage on the (y axis).

2. What is the shape of your line? Why do you think that is?

3. If an ammeter was hooked up to your circuit at 60˚ and the current was found to be .50 Amps, what would the power output of the solar cell be?

4. Just from looking at your lab data, at what angle do you think the sun was at? Why?

5. Why is it important to figure out an optimal angle for a solar panel? In other words, why not just have a solar panel that can change angles?

Lab 27— Series Parallel Lab

This is a difficult lab mostly because students have trouble turning a circuit diagram into a real circuit. It also requires students to know how to use a voltmeter to take a voltage across the light bulbs. The point of the lab is to show how series and parallel circuits differ and have students experience them

To do the lab, you need to build each of the circuits shown, and then measure the voltage across each. If you want to get fancy with the lab, you can use a CBL light sensor to detect the exact differences between dim and bright bulbs

Sample Items:1. in series, each should get half the total V

In parallel, each should get the same VParallel provides more voltage

2. The voltage should be the same for the bulbs added together as it was for the individual3. Again, the voltages in each branch should be the same4. The numbers should be the same again. This means that adding a branch does not affect the voltage in a previous branch5. Series: to increase the amount of current that must get to something (such as motors)

Parallel: to allow consistent voltage to multiple sources (light bulbs on a Christmas tree) even if the circuit is broken

Name:_______________________Period: ___

Physical Science—Parallel and Series Circuits

Questions:3. Does a series or a parallel circuit provide more voltage to light in a circuit?4. How is voltage “shared” in parallel labs?

Hypothesis:

Below, each resistor is a light bulb and the battery represents a 9 V battery.Build each of the below circuits. On the diagram, label:

direction the current is flowing the voltage each light bulb receives (you will need to use the voltmeter)

A

B

C

A B

CD

A

A

B

B

Circuit 1Circuit 2

Circuit 3

Circuit 4

Analyze1. Compare bulbs A and B in circuits 1 and 2.

How much voltage did each light bulb receive in the series?

How much voltage did each light bulb receive in the parallel?

Which kind of circuit provides more voltage to each of the light bulbs individually?

2. Look at circuit 3.How much voltage did A receive?

How much did B and C receive combined? (add B + C)

From this result, what can we say about the amount of voltage that goes through each branch of a parallel circuit?

3. Look at circuit 4.Which receives more A and D or B and C? (HINT: add A+B and compare to B+C)

Is this consistent with your answer from question 2?

4. Compare circuits 1 and 4.In circuit 1, how much does bulb A receive? How much does B receive?

In circuit 4, how much voltage does A receive? How much does D receive?

What does this tell us about bulbs that are in series inside a parallel branch? In other words, does the voltage of A and D have to be the same?

Conclusion:When would you use series circuits? When would you use parallel circuits?

Lab 28—Electromagnet Labs

This is one of the more “magic” labs that students are very surprised to actually see it work. This lab works best with new materials: new batteries and new nails. Make sure you don’t use galvanized nails, or they won’t magnetize! As for the wire, the beast option is to use non-coated copper wire. You will also need an ample supply of paperclips. Smaller paper clips are easier to pick up.

The lab is simple. Wrap the copper wire around the nail, hook up the battery, and use the nail to try to pick up paper clips. Although the procedure is easy, this lab comes with many student made mistakes. First, be sure students avoid overlapping the wire as much as possible. Students need to wind it as tight as possible without overlapping to prevent the wire from short circuiting. Next, make sure students have the current flowing from one end of the wire to the other. Quite often, student will attach the battery such that current does not actually flow through the wire around the nail. Next, make sure students don’t actually run the current through the nail as opposed to the wire. Finally, in essence, you are short circuiting the battery in this lab, so make sure students do not leave it plugged in too long which can cause the battery to heat up and potentially leak.

Sample Items:1. Graphs will vary2. Slopes will vary3. Paper clips/turns. Multiply the slope by 125 to find the number of clips.4. The magnetic poles are aligned creating a magnet5. V/R = I = 9 / 2400 = 3.75 mA

P = VI = (.00375)(9) = .034W

Name: ______________________Period: ____

Physical Science—Electromagnet Lab

Questions:How does an electromagnet work?

Research and necessary equations: Ohm’s Law—V= IR

Hypothesis:

Does increasing the number of turns around a wire increase the magnetism of a nail?

Is an electro magnet strong enough to move a compass needle?

Procedure/Analysis:1. Obtain a battery, a nail, wire, and a supply of paper clips.2. Wrap the wire around the nail, careful not to overlap the wire.3. Scratch of the coating of the wire at the two ends of the wire, and attach it to a battery.4. Use the tip of the nail to try and pick up as many paper clips as possible.5. Bring a compass near your nail and see if you can turn the needle.6. Add more coils and repeat step 4. Record your data below

Loops of Wire Number of Paper Clips picked up

25

50

75

100

125

150

Analysis:1. Create a graph of loops (independent) and paper clips picked up on the (dependent).

2. Find the slope of your line.

3. What is the unit of your slope? If you had 130 loops, how many paper clips do you think you could pick up

4. What is the difference between a nail without a wire wrapped around it and a nail with the wire around it? (HINT: your answer should have the word “pole” in it)

5. If the wire had a resistance of 2.4 kΩ, What is the current delivered by the 9V battery? What is the power output of the 9V battery?