Home Store Project Ideas Project Guide Ask An Expert Blog Careers Teachers Parents Students
Share to Classroom

Electrolyte Challenge: Orange Juice Vs. Sports Drink

Difficulty
Time Required Short (2-5 days)
Prerequisites None
Material Availability Specialty electronics items are required. A kit is available from Science Buddies. See the Materials list for details.
Cost Average ($40 - $80)

Abstract

The makers of sports drinks spend tens to hundreds of millions of dollars advertising their products each year. Among the benefits often featured in these ads are the beverages' high level of electrolytes, which your body loses as you sweat. In this science project, you will compare the amount of electrolytes in a sports drink with those in orange juice to find out which has more electrolytes to replenish the ones you lose as you work out or play sports. When you are finished, you might even want to make your own sports drink!

Objective

To investigate whether or not a sports drink provides more electrolytes than orange juice.

Credits

David Whyte, PhD, Science Buddies
Edited by Ben Finio, PhD, Science Buddies

This project is based on the following 2008 California State Science fair project, a winner of the Science Buddies Clever Scientist Award:
Yaeger, T.O. Jr. (2008). Electrolyte Madness.

Cite This Page

MLA Style

Science Buddies Staff. "Electrolyte Challenge: Orange Juice Vs. Sports Drink" Science Buddies. Science Buddies, 6 Feb. 2016. Web. 29 May 2016 <http://www.sciencebuddies.org/science-fair-projects/project_ideas/Chem_p053.shtml>

APA Style

Science Buddies Staff. (2016, February 6). Electrolyte Challenge: Orange Juice Vs. Sports Drink. Retrieved May 29, 2016 from http://www.sciencebuddies.org/science-fair-projects/project_ideas/Chem_p053.shtml

Share your story with Science Buddies!

I did this project I Did This Project! Please log in and let us know how things went.


Last edit date: 2016-02-06

Introduction

"Just do it!" You have probably heard that slogan, and there is no doubt that exercise is a key part of staying healthy. But exercising depletes the body's stores of fluids and minerals, which must be replaced. Most experts agree that if you are engaged in light to moderate exercise, drinking a glass or two of water should do the trick. But if you are exercising strenuously, you also need to replenish some of the salts that your body loses through sweat. These salts, or electrolytes, are found in most sports drinks, and also in natural juices like orange juice.

What advantages does a sports drink have over water? Water provides the liquid you need to avoid dehydration, but it does not have electrolytes. An electrolyte is a substance that will dissociate into ions in a solution. The ions in the solution give it the capacity to conduct electricity. Electrolytes, such as sodium and potassium, are present in sweat. Chloride, calcium, and phosphate ions are also electrolytes.

The proper concentration of electrolytes in your blood is essential to your health. Your cardiovascular and nervous systems—to name just two—require electrolytes to function well. Differences in the concentration of sodium and potassium inside and outside of cells allow your nerve and muscle fibers to send electrical impulses (which is how these cells communicate and get your body to react and move).

Your body keeps the concentration of the various electrolytes in its fluids within a narrow range, and this process depends on consuming enough water and electrolytes. The maintenance of electrolytes within this narrow range is due to the body's homeostatic mechanisms, which control the absorption, distribution, and excretion of water and its dissolved electrolytes.

To measure the electrolytes in this science project, you will use a multimeter. A multimeter is an electronic device that measures voltage, current, and resistance. You can learn more about these terms in the Science Buddies Electronics Primer. For this project, you will use just the ammeter part of the multimeter. An ammeter measures current. The procedure will describe what you need to do, but you can learn more about what a multimeter is and how to use one in the Science Buddies Multimeter Tutorial.

How can you use an ammeter to measure the concentration of electrolytes? You will use it to measure conductance, which is proportional to the electrolyte concentration. Because electrolytes are charged particles that carry current in solution, the conductance of the solution depends on the concentration of the electrolytes. If you increase the concentration of electrolytes in a solution, the conductance of the solution also increases. In order to measure a current in the solutions, you have to apply a voltage. You will use a 9 volt (V) battery to supply the voltage.

The symbol for conductance is G and it is measured in units called siemens (S). The symbol for current is I, and it is measured in amperes (A), commonly called amps for short. The symbol for voltage is V and it is measured in volts (also abbreviated V). Calculating the conductance is easy—it is the current divided by the voltage, as shown in Equation 1.

Equation 1.

  • G is conductance, measured in siemens (S).
  • I is current, measured in amperes (A).
  • V is the voltage, measured in volts (V).

Note that conductance is the inverse of resistance, which is measured in ohms (Ω, the capital Greek letter Omega). The symbol for resistance is R, so G = 1/R (1 S = 1 / Ω). Equation 1 is just another form of Ohm's law, which uses resistance instead of conductance: V = IR.

Finally, in this project the amount of current you will measure is fairly small. That makes it more convenient to take your measurements in milliamps (mA), thousandths of an amp; or microamps (μA), millionths of an amp. However, before you plug your current reading into Equation 1, you must convert the measurement back to amps. The procedure will explain how to do this.

Do not worry if you find it difficult to remember all the letters and symbols. Table 1 summarizes the electrical variables, their units, and abbreviations.

Quantity Variable Unit Unit Symbol
VoltageVVoltV
CurrentIAmpereA
ResistanceROhmΩ
ConductanceGSiemensS
Table 1. Electrical variables, their units, and abbreviations.

Terms and Concepts

  • Electrolyte
  • Dissociate
  • Ion
  • Solution
  • Conduct electricity
  • Electricity
  • Homeostatic mechanism
  • Multimeter
  • Voltage (V)
  • Current (I)
  • Resistance (R)
  • Ammeter
  • Conductance (G)
  • Proportional
  • Siemens (S)
  • Ampere, or amp (A)
  • Volts (V)
  • Ohms (Ω)
  • Ohm's law
  • Milliamp (mA)
  • Microamp (μA)
  • Open circuit
  • Short circuit
  • Direct current (DC)
  • Alternating current (AC)
  • Electrolysis
  • Dilute

Questions

  • What do electrolytes do in your body?
  • What advantages do sports drinks or juices have over water in terms of electrolyte content? Why does this matter for strenuous exercise?
  • Are there other reasons, besides electrolyte content, that you would pick a certain drink for before, during, or after strenuous exercise? For example, many juices have relatively high amounts of carbohydrates that add calories and require extra water to digest. Certain drinks might be more acidic and upset your stomach more easily. What other factors should you consider when picking a drink?
  • What are the amounts of calories, sodium, potassium, and carbohydrates in one serving (8 ounces [oz.]) of orange juice? How does this compare with sports drinks?

Bibliography

News Feed on This Topic

 
, ,
Note: A computerized matching algorithm suggests the above articles. It's not as smart as you are, and it may occasionally give humorous, ridiculous, or even annoying results! Learn more about the News Feed

Materials and Equipment Product Kit Available

These specialty items can be purchased from the Science Buddies Store:

  • Electrolyte Challenge kit (1). Includes:
    • Digital multimeter
    • Alligator clip leads (2)
    • Copper wire, bare, 24-gauge (1.5 meters [5 feet])
    • 9 V battery
    • 9 V battery clip
    • 1 kΩ resistor

You will also need to gather these items:

  • Disposable plastic straw
  • Scissors
  • Small plastic, glass, or ceramic bowls, not metal (8)
    • Use a different one for each liquid you test or use one bowl repeatedly, being careful to wash and wipe it thoroughly between liquids.
  • Masking tape or other materials for creating labels
  • Permanent pen or marker
  • Distilled water (dH2O), room temperature; available in the bottled water section of most grocery stores
  • Tap water, room temperature
  • Sports drink(s) of your choice, room temperature
  • Orange juice of your choice, room temperature
  • Paper towels
  • Lab notebook

Recommended Project Supplies

View Kit
Project Kit: $29.95

Share your story with Science Buddies!

I did this project I Did This Project! Please log in and let us know how things went.

Experimental Procedure

Making a Simple Conductance Sensor

  1. Using the scissors, cut a 5 cm (2 inch) piece from the drinking straw.
  2. With the scissors, cut two pieces of copper wire, each about 12 cm (5 inches) long.
  3. Make a conductance sensor, like the one shown in Figure 1.
    1. Wrap one piece of wire around the 5 cm straw piece near one end a few times, leaving a 5 cm (2 inch) tail of wire. Make sure you wrap the wire snugly around the straw. If the wires on the conductance sensor move while you are taking measurements, your measurements may be inaccurate.
    2. Wrap the second piece of wire around the other end of the straw tube a few times, leaving a 5 cm (2 inch) tail of wire. There should be no contact between the two pieces of wire, and they should be wrapped tightly enough that they will not slide off the straw.
    3. Caution: Make sure the two wires do not touch. The conductance sensor will not work if the wires touch, and touching wires will blow the fuse in your multimeter.
Figure 1: conductance sensor for measuring ions in solution
Figure 1. The conductance sensor consists of a non-conducting core (a piece of disposable drinking straw) with copper wire wrapped around the ends. The ions in the solution complete the circuit, enabling current to flow between the copper wires.

Making a Conductance Measuring Circuit

  1. Figure 2 shows a schematic of the main components of the circuit, and Figure 3 shows a detailed picture of the entire circuit. If you want, you can assemble your circuit just by looking at Figures 2 and 3. Otherwise, read the following detailed steps and refer to the figures as needed.
Electrolyte challenge science fair project circuit schematic
Figure 2. A schematic of how you should build the circuit. Use alligator clips to connect the red multimeter probe to the red battery lead, and the black multimeter probe to the conductance sensor. Make sure to connect the positive (red) wire of the battery clip to the port on the multimeter labeled VΩMA. Refer to Figure 3 to see how to connect the alligator clips.

Figure 3: science project setup for measuring ions in solution
Figure 3. This photo shows an example of the completed conductance measuring circuit.
  1. Connect the snap connector to the 9 V battery.
  2. For now, make sure your multimeter's center dial is in the "OFF" position. This will help avoid damage to your multimeter if you accidentally make a wrong connection.
  3. Plug the multimeter probes into the multimeter. The black (negative) probe goes in the port labeled "COM" at the bottom left of the multimeter. The red (positive) probe goes in the middle port, labeled "VΩMA". See Figure 4 for a close-up picture of how you should connect the probes. Make sure the multimeter probes are plugged into the correct ports, or your experiment will not work.
multimeter probes connected
Figure 4. A close-up picture of how you should insert the multimeter probes. The black probe goes in the port labeled COM and the red probe goes in the port labeled VΩMA.
  1. Use the red alligator clip lead to connect the positive (red) wire of the 9 V battery clip to the positive (red) multimeter probe. To do this, clip one end of the alligator clip lead to the exposed metal part of the positive (red) wire of the 9 V battery clip. Clip the other end onto the metal part of the positive (red) multimeter probe.
    1. Make sure to clip the alligator clips to the metal part of both the multimeter probe and 9 V battery clip wire, not the red plastic parts. The circuit will not work if the alligator clips are connected to the plastic, because plastic is an insulator and will not allow electricity to flow.
  2. Using the black alligator clip lead, attach one of the copper wire tails of the conductance sensor to the negative (black) probe of the multimeter. You can use either tail of the sensor. To do this, clip one end of the alligator clip lead to one of the wire tails of the conductance sensor, and clip the other end to the metal part of the negative (black) multimeter probe.
  3. Twist the other wire tail of the conductance sensor around the metal end of the black lead from the 9 V battery clip, as shown in Figure 5. Important: It is essential that you twist these wires together tightly, so they do not come loose. If the wires do not make good, consistent contact with each other, the circuit will not be complete and your experiment will not work. Make sure these wires do not get disconnected if they are bumped or moved during your experiment. If you have a pair of pliers, you can use them to squeeze or "crimp" the wires together and that will help them stay connected.
Figure 4: connect conductance sensor and battery
Figure 5. Twist one copper wire end of the conductance sensor around the metal part of the battery clip's black lead. Make sure you twist the wires together tightly so they do not come apart.
  1. Double-check your connections to make sure they match those shown in Figures 2 and 3. The order of the connections is important: the red probe of the multimeter should be inserted into the port labeled VΩMA, and connected to the red lead from the battery clip. The black lead of the battery clip should connect to one of the wire tails of the conductance sensor, and the other wire tail of the conductance sensor should connect to the black multimeter probe, which is inserted into the port labeled COM.
    1. Note that this is an open circuit because of the gap between the wires wrapped around the (non-conducting) straw. You will use the electrolytes in the solutions to close the circuit. The amount of current that flows is proportional to the electrolyte concentration.
  2. Important: Never let exposed metal from the red or black multimeter probes/alligator clips, or the conductance sensor wires, touch each other directly. This will create a short circuit. Since the circuit contains a 9 V battery, this could damage your multimeter by blowing out the fuse. Always keep the red and black wires a safe distance away from each other, as shown in Figure 3. Keeping your multimeter's dial in the "OFF" position when not in use will also help prevent accidental damage to your multimeter.

Setting Up Your Test Solutions

  1. Clean the eight small bowls with warm soapy water, rinse thoroughly, and dry them right away with a clean dry cloth or paper towel. This will remove ions in the tap water. If you want to be extra careful, rinse the bowls with distilled water before drying.
  2. Put masking tape on all eight bowls.
    1. Label four bowls with the following labels: Distilled Water, Tap Water, Sports Drink, and Orange Juice.
    2. Label one bowl Tap Water Rinse.
    3. Label the final three bowls as follows: dH2O Rinse 1, dH2O Rinse 2, and dH2O Rinse 3. Use these bowls to rinse the conductance sensor between uses.
  3. Pour each liquid into the appropriately labeled bowl. All of the solutions should be at room temperature. Each bowl should contain enough liquid to completely submerge the straw part of the conductance sensor, as shown in Figure 3.

Measuring the Conductance

  1. Set your multimeter to measure direct current in the 200 μA range. This is the green "200μ" on the upper-right part of your multimeter dial, as shown in Figure 6. This is a high-sensitivity setting that you will only use to measure distilled water, which is less conductive than the other liquids.
    1. Note: To save space, the multimeter does not have an "A" next to every setting to measure current. There is a single green A with straight dashed and dotted lines next to the current measurement settings, which are also in green (shown in Figure 6). The "A" stands for "amperes" and the straight lines represent direct current (DC), which stays constant over time. This is different from a squiggly line which represents alternating current (AC), which changes over time. Your multimeter also has other settings, like those for measuring DC voltage (white V with straight lines), AC voltage (white V with squiggly line), and resistance (green Ω). In this project you will only use the direct current settings (those by the green "A"). You can read more about what the symbols on the front of a multimeter mean in the Multimeter Tutorial.
multimer 200 microamp DC setting
Figure 6. Multimeter dial set to the 200 microamp (μA) range, represented by the green "200μ."
  1. Place the conductance sensor in the distilled water. Make sure the straw is completely immersed.
  2. Read the current on the multimeter.
    1. Always make your readings quickly and remove the conductance sensor from the solutions immediately. Over time, the copper wires will start to dissolve in the solutions, skewing your results. In addition, electrolysis may take place, forming tiny bubbles on your conductance sensor that can interfere with your data.
    2. Your readings may fluctuate slightly, and this is normal. Try to record an "average" reading, or a number in the middle of the range that you observe.
  3. Record the current (the readings from your multimeter) in your lab notebook in a data table. Make sure to record that this reading is in microamps (μA). Remember that a microamp is one millionth of an amp.
  4. You do not need to rinse your conductance sensor this time because you used distilled water.
  5. Now set your multimeter to measure direct current in the 200 mA range. This is the green "200m" on the right side of the multimeter dial, as shown in Figure 7. This setting can measure higher current values, which you need to do for the more conductive liquids.
multimeter 200 milliamp DC setting
Figure 7. Multimeter dial set to the 200 milliamp (mA) range, represented by the green "200m". Be careful not to get this mixed up with the white "200m" on the other side of the dial. That setting is for measuring voltage, not current.
  1. Now place the conductance sensor in the tap water.
  2. Record the current. Again, make sure you record the correct units. Since your multimeter dial is set to 200m, this reading is in milliamps (mA), not microamps (μA).
  3. Tap the sensor on a paper towel to remove drops of tap water. Then rinse the sensor in distilled water, dipping it briefly in each of the three distilled water rinse bowls.
  4. Place the sensor in the sports drink and measure the current (you do not need to change the multimeter dial). Record the current in your lab notebook, and remember to record units of milliamps.
  5. Tap the sensor dry, and then dip the sensor in tap water, then in the three bowls of distilled water.
  6. Place the sensor in the orange juice and measure the current. Record the current in your lab notebook.
  7. Rinse the sensor in the tap water and then in all three distilled water bowls.
  8. Repeat steps 1–13 in the "Measuring the Conductance" section two more times to obtain a total of three measurements for each liquid.
    1. Remember that you will need to switch back to the "200μ" setting to measure the distilled water, and then use the "200m" setting to measure tap water, sports drinks, and orange juice.
    2. Record all data and measurements, including the proper units, in the data table in your lab notebook.
  9. Average your current measurements across the three trials for each liquid.
  10. Before you proceed, convert all of your current measurements to amps (A).
    1. Convert microamps (μA) to amps (A) by dividing by 1,000,000. For example, 20 microamps is 0.00002 amps (20/1,000,000 = 0.00002).
    2. Convert milliamps (mA) to amps (A) by dividing by 1,000. For example, 20 milliamps is 0.02 amps (20/1,000 = 0.02).
  11. Calculate the conductance for each liquid by using Equation 1 from the Introduction.
    1. The current (I) for each liquid is the average current that you calculated. Make sure you convert the current to amps. Do not use milliamps or microamps in Equation 1.
    2. Since the voltage was always from your 9 V battery, you can use 9 V as the voltage (V) in your calculations. In reality, the voltage is likely to be slightly less than 9 V due to internal resistance of the battery. But this change is quite small and nearly constant across the experiment. Because it is so small, you do not need to take it into account. If you have a second multimeter, you can adapt the circuit to monitor both current and voltage across the battery at the same time.
  12. Which liquid has the highest conductance, meaning the most electrolytes?

Troubleshooting

For troubleshooting tips, please read our FAQ: Electrolyte Challenge: Orange Juice Vs. Sports Drink.

Share your story with Science Buddies!

I did this project I Did This Project! Please log in and let us know how things went.


Variations

  • Try other sports drinks and juices.
    1. What is the conductance of fresh-squeezed orange juice?
    2. What about the conductance of lemonade?
  • Try making your own sports drink, starting with orange juice. If the carbohydrates in the orange juice are higher than they are in the sports drink, dilute the juice with distilled water so that the carbohydrates are about the same as they are in the sports drink. How does the conductance of the diluted juice compare to that of the sports drink?
  • Standardize your readings, using tap water as a reference. Divide all of the current measurements for each trial by the current you measured for the tap water. Tap water will have a conductance of 1.0. The fruit juice and sports drinks will then have conductances that are multiples of the tap water's conductance.

Share your story with Science Buddies!

I did this project I Did This Project! Please log in and let us know how things went.

Frequently Asked Questions (FAQ)

If you are having trouble with this project, please read the FAQ below. You may find the answer to your question.
Q: I am not sure if my multimeter is set up correctly. How should it be configured?
A: The multimeter dial has a lot of different settings, which may seem confusing at first. In this project, you will only use the green "200μ" and "200m" settings, which measure direct current in the 200 microamp (μA) and 200 milliamp (mA) ranges, respectively. These settings are shown in Figures 6 and 7 of the procedure. You also must make sure the black multimeter probe is plugged into the port labeled "COM", and the red probe is plugged into the port labeled "VΩMA". You will not need to use any of the other settings on your multimeter for this project. If you want to learn more about what the other symbols mean, refer to the Multimeter Tutorial.
Q: My multimeter always reads 00.0 when I try to measure current. What am I doing wrong?
A: A number of issues may result in a reading of 00.0 from the multimeter, regardless of the solution's real conductance:
  • One or more of the connections in your circuit may not be attached securely. If just one connection is loose, this will prevent the circuit from being complete, and the multimeter will be unable to take a reading. Double-check all of your alligator clips and the wire twisted to the black battery snap lead. Make sure all these connections are snug with metal-on-metal contact (do not clip to any of the plastic, since plastic is an insulator).
  • You might not have your multimeter on the correct setting. The currents flowing through the liquids in this experiment are very small, so your multimeter must be set at a high sensitivity. Use 200 microamps (μA) for distilled water, and 200 milliamps (mA) for the other liquids. See Figures 6 and 7 in the Procedure for instructions on how to set your multimeter.
  • You might not have your multimeter's probes in the correct ports. Make sure the black probe is in the port labeled "COM" and the red probe is in the port labeled "VΩMA." See Figure 4 in the Procedure.
  • The 9 V battery in your circuit might be dead. This is unlikely if you are using a fresh battery from your Science Buddies kit, but the battery could drain if you accidentally left the circuit connected for a long time. You can check whether your battery still works by setting your multimeter to read 20 V DC (labeled "20" in white text on the left side of the multimeter dial) and placing the positive (red) multimeter probe on the positive battery terminal (marked with a "+" sign), and the negative (black) multimeter probe on the negative battery terminal (marked with a "-" sign). If the reading is below 7, your battery may not have enough power for this project and you should use a fresh battery.
  • The wires on your conductance sensor may have become compromised in some way. There should be no material collected on them; if there is anything collected on them, clean and rinse them well and try again.
  • Your multimeter may have blown a fuse. The fuse contains a thin wire that burns out if too much current flows through it, in order to protect the rest of the multimeter's circuitry. When the experiment is set up as described, but the two sensor wires (in the liquid) touch, it will blow the fuse, so be sure they do not touch. If your multimeter was working well and then suddenly starting reading 00.0 all the time, there is a chance you blew the fuse in your multimeter (there is also a chance that one of your connections simply came loose. See the first bullet point above). See the question "How can I tell if I blew the fuse in my multimeter?" to confirm if you blew the fuse.
Q: What does it mean if I am getting a negative current reading on my multimeter?
A: The wires in the circuit may be connected incorrectly, resulting in current flowing "backwards" through your circuit. Double-check all your connections against Figures 2 and 3 in the Procedure. For example, if you connect the battery backwards (switch the red and black leads), or get the red and black multimeter probes switched, that will result in a negative current reading.
Q: Why are my multimeter readings going up and down?
A: A few possibilities could explain why your readings are fluctuating; you can determine what is happening in your experiment by how much the readings are changing.
  • It is normal to have very small fluctuations (for example, the reading stays around the same number but increases or decreases slightly). In these types of experiments with multimeters, it can be very difficult to get an entirely stable current.
  • If your measurements decreased quickly, you may have encountered a problem with electrolysis. Electrolysis is when water is broken up into hydrogen and oxygen gas by an electrical current. If electrolysis is occurring, there will be little bubbles collecting on the wires on the ends of the conductance sensor. Electrolysis will result in a smaller surface area on the wires on the conductance sensor, and your readings will decrease. If you notice this occurring, rinse of your sensor and try again, and take your reading quickly before lots of bubbles accumulate on the sensor.
  • If the wires on the conductance sensor move while you are taking measurements, this can make your measurements randomly vary from sample to sample. To fix this, see the answer for the question "Why is it important to keep the wires on the conductance sensor from moving?"
Q: The current readings on my multimeter seem very low for all of my samples and there is not much variation between them. What should I do?
A: Your multimeter may not be configured correctly. To check this, see the answer for the question "I am not sure if my multimeter is set up correctly. How should it be configured?" Alternatively, the 9 V battery in your circuit may be dead. To test the battery, see the fourth bullet point for the question "My multimeter always reads 00.0 when I try to measure current. What am I doing wrong?"
Q: I am not sure if the values I am getting are correct. How should I be making my calculations and what is the range that my results will probably fall in?
A: If you take your measurements using the 200 milliamps setting, your current readings will be in milliamps (mA). If you used the 200 microamps setting with the distilled water, your current readings will be in microamps (μA). For this experiment, current readings in the range of 0 (for distilled water) to 100 mA (for the other liquids) are expected.

To calculate the conductance of your different samples, use Equation 1 from the Introduction. Convert your current readings from microamps or milliamps to amps, as described in step 16 of the Procedure. Divide this by the voltage of your battery (which should be about 9 V, but you can measure this with your multimeter to be sure, as described in the fourth bullet point under "My multimeter always reads 00.0 when I try to measure current. What am I doing wrong?"). This will give you conductance in siemens (S), which you can convert to millisiemens by multiplying by 1,000.
Q: Why is it important to keep the wires on the conductance sensor from moving?
A: If the wires on the conductance sensor move while you are taking measurements, your measurements may be inaccurate. Make sure the wires are tightly secured on the ends of the conductance sensor by attaching the short end of the wire to the longer end by twisting the two together, or by using a very small drop of super glue to hold the wires in place.
Q: What is the purpose of dipping the sensor in distilled water? Should I replace the distilled water between tests?
A: Dipping the sensor in distilled water removes all of the ions and other liquids from the sensor. Not rinsing the sensor will cause the sensor to become contaminated with different liquids between the different tests, which could make your results have higher or lower conductance values than they actually do. Although it is not necessary, changing the distilled water in the rinsing bowls between tests may improve accuracy.
Q: How can I tell if I blew the fuse in my multimeter?
A: Follow these steps (if you already started your experiment, you might already have made some of these connections, like attaching the snap connector to the battery):
  1. Plug the multimeter's black probe into the port labeled "COM," and the red probe into the port labeled "VΩMA," as shown in Figure 4 in the Procedure.
  2. Your kit includes a 1 kΩ resistor, a small tan cylinder with two metal leads sticking out of it. Tightly wrap one lead from the resistor around the end of the black probe tip, as shown in Figure 8. Connecting the resistor is essential in order to avoid blowing out the fuse in your multimeter.
  3. Attach the snap connector to the 9 V battery.
  4. Use the black alligator clip lead to connect the free lead from the resistor to the snap connector's black lead.
  5. Use the red alligator clip lead to connect the multimeter's red probe to the snap connector's red lead. Your completed circuit should look like the one in Figure 9.
  6. Important: Do not let any exposed metal from the red and black alligator clips or multimeter probes touch each other. This will create a short circuit and could blow your multimeter's fuse.
  7. Set your multimeter to measure direct current in the 200 mA range (the dial setting labeled "200m" on the right, as shown in Figure 7 in the Procedure).
  8. Your multimeter should read about 9 mA (maybe slightly less if you are not using a fresh battery).
    1. If this works, then you know there is nothing wrong with your multimeter. If you are having trouble with your experiment, the problem is with something other than the multimeter.
    2. If this does not work, and you are confident that you set up the test correctly, as shown in Figure 9, please contact help@sciencebuddies.org for assistance.
  9. When you are done, disconnect the alligator clips so you do not drain the 9 V battery, and remember to turn your multimeter off.
1k resistor wrapped around multimeter probe
Figure 8. A close-up picture showing one of the resistor's leads wrapped around the black multimeter probe tip.
setup to determine if a multimeter has a blown fuse
Figure 9. Setup for making sure the multimeter has a working fuse.

Q: My multimeter's screen just remains blank when I turn it on. Is it broken?
A: If you turn your multimeter's dial to the 200 μA or 200 mA settings, as described in Figures 6 and 7 of the Procedure, the screen should read "00.0" when the multimeter is not connected to anything (or when the conductance sensor is not immersed in a liquid). If your screen remains blank, then you might have a defective multimeter. Contact us at help@sciencebuddies.org for assistance.

Ask an Expert

The Ask an Expert Forum is intended to be a place where students can go to find answers to science questions that they have been unable to find using other resources. If you have specific questions about your science fair project or science fair, our team of volunteer scientists can help. Our Experts won't do the work for you, but they will make suggestions, offer guidance, and help you troubleshoot.

Ask an Expert

Contact Us

If you have purchased a kit for this project from Science Buddies, we are pleased to answer any question not addressed by the FAQ above.

In your email, please follow these instructions:
  1. What is your Science Buddies kit order number?
  2. Please describe how you need help as thoroughly as possible:

    Examples

    Good Question I'm trying to do Experimental Procedure step #5, "Scrape the insulation from the wire. . ." How do I know when I've scraped enough?
    Good Question I'm at Experimental Procedure step #7, "Move the magnet back and forth . . ." and the LED is not lighting up.
    Bad Question I don't understand the instructions. Help!
    Good Question I am purchasing my materials. Can I substitute a 1N34 diode for the 1N25 diode called for in the material list?
    Bad Question Can I use a different part?

Contact Us

Related Links

If you like this project, you might enjoy exploring these related careers:

Scientists inspecting special corn oil

Food Scientist or Technologist

There is a fraction of the world's population that doesn't have enough to eat or doesn't have access to food that is nutritionally rich. Food scientists or technologists work to find new sources of food that have the right nutrition levels and that are safe for human consumption. In fact, our nation's food supply depends on food scientists and technologists that test and develop foods that meet and exceed government food safety standards. If you are interested in combining biology, chemistry, and the knowledge that you are helping people, then a career as a food scientist or technologist could be a great choice for you! Read more
nutritionist helping client

Dietitian or Nutritionist

Ever wondered who plans the school lunch, food for patients at a hospital, or the meals for athletes at the Olympics? The answer is dietitians and nutritionists! A dietitian or nutritionist's job is to supervise the planning and preparation of meals to ensure that people—like students, patients, and athletes—are getting the right foods to make them as healthy and as strong as possible. Some dietitians and nutritionists also work to educate people about good food choices so they can cook and eat their own healthy meals. Read more
Picture of chemist

Chemist

Everything in the environment, whether naturally occurring or of human design, is composed of chemicals. Chemists search for and use new knowledge about chemicals to develop new processes or products. Read more
Female athletic trainer helping woman lift weights.

Athletic Trainer

Sports injuries can be painful and debilitating. Athletic trainers help athletes, and other physically active people, avoid such injuries, while also working to improve their strength and conditioning. Should a sports injury occur, athletic trainers help to evaluate the injury, determine the treatment needed, and design a fitness regime to rehabilitate the athlete so he or she is ready to go out and compete again. Read more

News Feed on This Topic

 
, ,
Note: A computerized matching algorithm suggests the above articles. It's not as smart as you are, and it may occasionally give humorous, ridiculous, or even annoying results! Learn more about the News Feed

Looking for more science fun?

Try one of our science activities for quick, anytime science explorations. The perfect thing to liven up a rainy day, school vacation, or moment of boredom.

Find an Activity