Abstract

Objective

In this experiment you will test if the number of rubs of wool on a balloon increases or decreases how long the static charge will last.

Introduction

Static electricity is the build-up of electrical charge in an object. Sometimes static electricity can suddenly discharge, like when a bolt of lightning flashes through the sky. Other times, static electricity can cause objects to cling to each other, like socks fresh out of the dryer. The static cling is an attraction between two objects with different charges, positive (+) and negative (−).

You can create static electricity by rubbing one object against another object. The rubbing produces friction which releases negative charges, called electrons, that build up to produce a static charge. When you shuffle your feet across a carpet the friction causes a static charge to build up inside of you. You can suddenly discharge this static electricity when you touch a friend to send them a shock. When you rub a balloon on your head the friction causes opposite static charges to build up in your hair and in the balloon. You can see these two opposite static charges attracting each other when you pull the balloon slowly away from your head making your hair stand up.

Static electricity makes your hair stand up! (NASA, 2004)

In this experiment you will test if the number of rubs can change how long the static charge will last by rubbing a balloon with wool and timing how long it will cling to a wall. By doing this experiment you can investigate how to create static electricity and how static charge is affected by friction.

Terms, Concepts, and Questions to Start Background Research

To do this type of experiment you should know what the following terms mean. Have an adult help you search the Internet, or take you to your local library to find out more!

• static electricity
• static charge
• attraction
• friction

• How does friction produce static electricity?
• How is static electricity related to charge?
• How can you measure static electricity?

Bibliography

• Science Made Simple, 2005. "Static Electricity: What Causes Static Shocks?" Voorhees, NJ: Science Made Simple, Inc. [accessed: 3/18/06] http://www.sciencemadesimple.com/static.html
• Loney, D., 2006. "Hair-Raising Science: Static Electricity," American Chemical Society. [accessed: 3/18/06] http://www.chemistry.org/portal/a/c/s/1/feature_tea.html?id=be98b66208ff11d6f2406ed9fe800100
• NASA, 2004. "Runaway Soda," Kids Features, National Aeronautics and Space Administration (NASA). [accessed: 3/18/06] http://www.nasa.gov/audience/forkids/activities/A_Runaway_Soda.html
• Brynie, F.H., 2005. Parents Crash Course: Elementary School Science Fair Projects, Hoboken, NJ: Wiley Publishing Inc. pp 124-130.

Materials and Equipment

• balloon
• woolly sweater, scarf, or blanket
• stopwatch
• notebook and pencil
• graph paper

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Experimental Procedure

1. For this experiment, you will need a data table for your results. You will need one data table for each trial, so make at least three data tables for doing at least three separate trials. A sample data table looks like this:

   Trial	Number of Rubs	Stays on Wall? (Y/N)	Time on Wall (seconds)

2. Blow up the balloon and tie off the end.
3. Rub the balloon on the scarf once, in one direction.
4. Hold the balloon up on the wall, start the stop watch and release. Does it stay on the wall? If not, stop your stop watch and write "0 seconds" in your data table.
5. Touch the balloon to a metal object. This should discharge any extra electrons into the metal.
6. Repeat steps 3 to 5, increasing the number of rubs each time until the balloon sticks to the wall. When you increase the number of rubs do not rub the balloon back and forth, rub the balloon in the same direction each time.
7. When the balloon does stick to the wall, keep the stop watch going until the balloon falls off of the wall. When it does, stop the stop watch and write the time in the data table next to the matching number of rubs.
8. Repeat step 7, increasing the number of rubs each time and recording the amount of time the balloon sticks to the wall with the stop watch. Write the results in the data table each time.
9. Make a graph of your results. A line graph is the best type of graph for this experiment. Make a scale on the left side of the graph (Y-axis) for the number of rubs, and a scale on the bottom of the graph (X-axis) for the time in seconds. For each point of data, make a dot where the number of rubs and the time in seconds intersect.
10. Does your data make a line? Does the line go up or down? Does the line level off at some point, or keep going? Does the time the balloon stays on the wall increase or decrease with the number of rubs?
11. You can repeat the experiment a few more times and graph the results. Does the data for each trial match with the previous trials?

Variations

• Does rubbing in one direction give a different result than rubbing back and forth? Try a different experiment comparing the same number of rubs in one direction compared to back and forth. Does one stay up on the wall longer than the other?
• Static electricity is not good when it gets in your clothes! How do dryer sheets work? Try an experiment rubbing the balloon with a dryer sheet (like Bounce) after rubbing against the wool. What happens to the static cling? Can you rub different times, measure the results and make a graph? If you can, you can make a graph to compare the results of different products. How do they compare? Do they take the same number of rubs to reduce the static cling? Which brands are most effective?
• Try comparing the effectiveness of different materials for producing a static charge. Does rubbing wool work better than rubbing silk? Design an experiment. to test several different materials: silk, wool, nylon, polyester, plastic, metal, etc.
• For a more advanced experiment, try investigating static electricity in different conditions, temperatures and humidities (Brynie, 2005).

• For more science project ideas in this area of science, see Electricity & Electronics Project Ideas.

Credits

Sara Agee, Ph.D., Science Buddies

Last edit date: 2012-01-12 12:00:00