Detecting the Electric Field

You are actually fairly familiar with electric fields too, but you may not know it. Have you ever rubbed your feet against the floor and then shocked your brother or sister? Have you ever zipped down a plastic slide and noticed that your hair is sticking straight up when you get to the bottom? Both phenomena are caused by electric fields and they are everywhere!

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43 Responses to “Detecting the Electric Field”
  1. Aurora says:

    It’s based on the idea that atoms atoms are mostly empty space, and it’s the charges that hold things together. You and I feel solid, the table and chairs feel solid, the ground feels solid, right? That’s because of the forces that keep everything from flying apart. Inside each little atom is a nucleus in the center and a cloud of electrons around it. If the atom was the size of the earth, the nucleus would be the size of a football field… so most of the space between that football field and the surface of the earth would be empty space. It’s the forces that hold the atoms together that we get that “solid” feeling from. Does that help?

  2. hollynoble says:

    When you were talking in the Force introduction reading about friction and how a person doesn’t sit on a chair, it’s just the electromagnetic field around a person’s atoms and the chairs atoms that are touching — could you explain that a little bit more please? I can actually feel the chair when I sit in it, so it really feels like my matter is touching the chair’s matter. Thanks.

  3. Aurora says:

    Sure – I bet you can figure something out! 🙂

  4. Nohemi Pitts says:

    Hi Aurora!

    We are just getting this project under hand. Can you make one with SUPER fun things like a volcano or something?

  5. Aurora says:

    I’ve had that happen to me also! It’s usually from the friction of the wheels picking up a charge and then storing it on the grocery cart, and because it’s metal it distributes the charge over the whole cart. And the wheels are constantly rubbing as you wheel your way down the aisle, so it’s constantly picking up more and more charge. Notice that you only get a shock when you remove or place your hand on the cart… if you keep in direct contact with the cart, you don’t constantly get shocked.

  6. Andrea Rosario says:

    Hi Aurora,

    This was a fun experiment. Thank you! I was wondering how you can get shocked and/or have the ability to touch other people and shock them when you’re in a grocery store. It comes from the metal in the cart, right? Why does it happen?

    I appreciate your time!
    Arteah Rosario

  7. Aurora says:

    Awesome idea Daniel!

  8. Hertha McLendon says:

    I made my own project !! for this project you need 3 high quality magnets. stack 2 of them in a T shape so one pulls and one pushes. then put the other magnet close so it should go up and down. daniel 8 yrs. old. you can try it !!!!!

  9. Aurora says:

    Static charge is an ELECTRIC charge (positive and negative), and magnetism has north and south poles. What do you think would happen? (Did you try it?) There’s a whole section in the upper level physics section on how magnetism and electric charge work together.

  10. Miranda Risinger says:

    what would happen if you put a magnet next to a balloon that you rubbed on your hair ?

  11. Aurora says:

    Electricity, not energy. They are two totally different things. It’s the charge that made them move, not energy. 🙂

  12. Evelyn Arevalo says:

    that was cool how the energy can make it move! ( ; ( ; ( ;

  13. Aurora says:

    You’ll want to watch the video and see if you can rig up something that does the same thing. It doesn’t have to measure anything – you just need something about 3 feet long and lightweight. I got mine for free at our craft store, but I also know some hardware stores carry them very inexpensively.

  14. Michelle Palmer says:

    I have a 12″ ruler, will that work or must I buy a yard stick?

    I’ve already looked locally and no one has yard sticks. I’d have to order online and with shipping makes them quite expensive.


  15. Aurora says:

    Yes – you need to be logged in in order to download it. What web browser are you using? You can switch to another if it is not coming up as a link – there was a recent update in one of them that inactivates the links, but my team is working on fixing it right now.

  16. Kathy Gochee says:

    Hi! Should there be a link below this video to download worksheets and exercises?

    Thank you

  17. Aurora says:

    Great question! We cover this in the Electricity Teleclass, but here’s the main idea:

    Going back to our water analogy, the water pressure is like voltage (volts), and the volume of water, or quantity, is current, or amps.

    If you are standing in a stream, there might be a lot of water going by you, but it’s not high pressure so it doesn’t hurt and you can stand still in it. It’s low voltage but high amperage, like a car battery (700 amps at 12 volts)

    Compare that with a firehose, which if you put the firehose next to the stream, there’s not nearly as much water coming out of the firehose as coming out of the stream, but if you were to get spayed with it, it would knock you over. The firehose is low amperage and high voltage, like a static van de graff machine (half million volts at 3 microamps), or like the zap you get when you scuff across the carpet.

    An example of high amps and high volts is like the Colorado river in spring – it’s wild, raging, and has a lot of water pouring out of it, like a bolt of lightning.

  18. Vesta mORGAN says:

    You mentioned that even though the charge may have thousands of volts, because of low amperage you are not harmed. What happens when there is high amperage and low volts?

  19. Aurora says:

    You just need something thin, long, and light that doesn’t conduct electricity (wood or plastic are good choices). I listed a yardstick because it’s something most people have in their house already, but yes… by all means improvise and use what you have!

  20. Katie Barr says:

    It stinks I don’t have a yardstick or meter stick would a ruler work?

  21. Aurora says:

    If you haven’t yet tried it, you should look at “Jupiter’s Jolts” experiment!

  22. Aurora says:

    The triboelectric series is a list that ranks different materials according to how they lose or gain electrons. Near the top of the list are materials that take on a positive charge, such as air, human skin, glass, rabbit fur, human hair, wool, silk, and aluminum. Near the bottom of the list are materials that take on a negative charge, such as amber, rubber balloons, copper, brass, gold, cellophane tape, Teflon, and silicone rubber. This list is compiled by actually doing the experiments and seeing which one is attracted to a known charge to determine which is which.

    Here’s a list for your reference:

    Most Positive (+)

    Human Hands, Skin
    Rabbit Fur
    Human Hair
    Cat Fur
    Sealing Wax
    Hard Rubber
    Synthetic Rubber
    Gold, Platinum
    Acetate, Rayon
    Orlon, Acrylic
    Cellophane Tape
    Polyvinylidene chloride (Saran)
    Polyvinylchloride (Vinyl)
    Silicone Rubber

    Most Negative (-)

  23. Lauren Doty says:

    We have a question about the answer to #1 on the Exercise sheet: What happens if you rub the balloon on other things, like a wool sweater? We thought the answer should be a negative charge. We used a piece of wool instead of hair to charge our balloons. Why would it be a positive charge? (Thanks – we had a lot of fun making the yardstick move!)

  24. Aurora says:

    Hi Alex,

    I think you’re asking what causes magnetism, is that correct? If so, it has to do with electron spin. There’s a whole section on this in Unit 11!

  25. Mary Silvernagel says:

    Hi there. Alex would like to know why opposites attract. Thanks, Mary Beth

  26. Tara Romsaithong says:

    We are using the program in a classroom setting. I asked the students to provide a more detailed write-up of what we did in class. Here’s what one student had to say.
    “We did an experiment on testing the Electric Field. Our teacher divided us into two groups. My partner and I got a wooden ruler and a wooden spoon. [teacher note: other groups used a metal yard stick and metal spoon] The teacher asked us how we could move the ruler with static electricity. Then she gave us a balloon to blow up. I rubbed it on my hair and moved it slowly toward the ruler. We did four tests. On the 1st test, it did not spin. On the 2nd test, it could spin. On the 3rd test, it spun all around the table. On the 4th test, it did not spin. Then another team had an idea. They used a Lego spinner in replacement of the spoon. It spun perfectly!
    For some extra fun, we rubbed the balloon on our hair really hard and tried sticking it to the wall. It would not stick, but I felt a little tug everywhere I tried to hang it. There was only one kid in the whole class that had hair that could make the balloon stick anywhere!”

  27. Aurora says:

    As you probably know, your daughters ability to shock her brother comes from the build up of static electricity on her body. This happens when excess electric charge (positive or negative) is collected by your body and doesn’t have any outlet to escape to. When one person with built up electric charge touches another person who is electrically neutral (having no excess charge), the charge moves between the two to make them electrically neutral relative to each other. The same thing happens if a person with built up static electricity touches other objects that conduct electricity, such as metal doorknobs or handles.

    Current is the flowing of charge from one place to another. It’s this current that exists between an electrically charged person and an electrically neutral object that creates the shock felt in the skin as they touch. To quote Wikipedia on static electricity, “the feeling of an electric shock is caused by the stimulation of nerves as the neutralizing current flows through the human body.” The current flowing between two people during static discharge is the same strength for both people, which leads me to believe that the reason sometimes one person feels the shock more than the other is due to the sensitivity of each person’s nerves at the point of contact. For instance, if your daughter touched your son with her finger on his arm to create a shock, it would probably be felt by both but it might be more intense for him due to the increased sensitivity of the nerves in his arm versus her finger. Plus, if she knew she was going to shock him but he was unaware of her plan until she touched him, the surprise of the shock might add intensity to the brief zing he felt.

  28. riggfamily says:

    My daughter was “shocking” her brother in the store the other day and we wondered why sometimes both people feel the shock and other times only one person feels the shock. I am thinking it has to do with the charge of each person, but wasn’t sure.

  29. Aurora says:

    Static electricity is generated when one substance rubs against another. For example, moving your shirt over your head (hair) can easily create static electricity if conditions are right. In this case your body will be charged with static electricity. Electricity needs a conductor to be able to move away from the source of electricity. If there is no conductor the electric charge will stay where it is. Water is a conductor. Humidity is a term that tells us how much water, in the form of vapor, is in the air. High humidity means there is a lot of water in the air. The more water there is in the air the more conductive the air becomes. This means that in a very dry (low humidity) environment, static electricity cannot move away. The air acts as an insulator. However, in a humid situation, air becomes a conductor and it will become very hard to have an object, like your body, to accumulate static electricity.

  30. Fiona Leonard says:

    Just noticed your comment re humidity. We did this experiment in one room with air conditioning and it worked beautifully then we tried to replicate it in another room and couldn’t raise any static at all. We eventually concluded it had to be the humidity – we’re in Ghana, so nice and near the equator!

    Why does the humidity level affect the static?

  31. Aurora says:

    It’s fun experiment! You can find it here:

    Also – I am working on how to make a whole set of static electricity inventions and machines – look for it in my e-Camp this summer.

  32. verna chiang says:

    You make reference to a “static electricty motor” in the video.

    Where is this?

  33. Aurora says:

    Yes, humidity will make this experiment difficult, if not impossible. You can close the windows and crank up the heat to dry out the air and see if that helps. The kind of ruler doesn’t make that much of a difference, although a metal one seems to be the hardest to move around.

  34. Marcia Mellor says:

    Hi Aurora!
    My daughter and I did this experiment today and I’m not sure why rubbing the balloon on my hair produced the ruler to move but sadly after rubbing the balloon on her hair several times sadly we couldn’t seem to get the ruler to budge? I used a plastic 60 cm ruler in the experiment. Are there any factors that could have effected the outcome? It was a high humidity day today??

  35. Aurora says:

    Yes, you’re right – we’ve had several requests for this feature to be added, and we have already started to do this with the newer experiments on the site and are gradually changing over the older ones as well. Since there are over 600 experiments, this task is going to take awhile, so thank you for being patient.

  36. Lee Giles says:

    Can each experiment start with a list of materials? Without reading through each one I don’t know which experiments need which supplies. I don’t want my son getting excited over doing an experiment we can’t do because we don’t have the supplies. I want to know which experiments we’re able to do up front. This could be done right on the shopping list or on the experiments page. We are an overseas family and something like a quarter is hard to come by. We don’t just have all those household items always on hand.

  37. Aurora says:

    Good question Christine! You can hook up a fish or spring scale to find the force exerted by a magnet, but it’s not easy to do, as the force decreases by the ‘inverse square law’ the further away from the magnet you are. (At twice the distance, the force has dropped by a quarter). Hold the gauss gun near horizontal to eliminate your errors because yes, you would need to account for the angle the ruler makes with the horizon. You can ‘back-calculate’ the force of the magnet by measuring the speed of the ball as it flies off the ruler (measure the time it takes for the ball to travel a set distance… the smaller this distance, the more accurate your calculation will be). Then use momentum (mass * velocity) and see if your m1v1 is the same as your m2v2. (State 1 is your initial ball and state 2 is the last ball coming off the track.) I assume that’s what you’re doing when you say ‘test the law of momentum… is that right?

    You’re going to get strange answers, though, as you’ll need to account for the magnets in your momentum equation, as the state 1 ball has the magnetic force as an addition to the momentum, but the state 2 ball will have it subtracted from the momentum (the ball needs to break free of the magnet). This problem would be a challenge for my undergraduate students in engineering! 🙂

  38. Christine Cormack Christine Cormack says:

    We are trying to test the law of conservation of mometum using a gauss gun. We need to measure the force of the magnet. Can the force of the magnetic field be measured simply measuring the weight of what a magnet can hold against granvity? If you are operating a gauss gun at only a slight angle, do you then need to add the force of gravity to that weight to determine the magnet strength? ( We have an angle to our track to try to elimiate the variable of the amount of push with each lauch–gravity provides a constant start speed. Does that make sense?)

  39. Aurora says:

    Whoops – when we did a little housekeeping and reorganized the earlier experiments, this one was whisked away into a black hole! It should work fine now. Sorry for the trouble!

  40. Katie Archer says:

    I have encountered the same error message as Kimberly. We would like to be able to view the experiments also.

    Thank you,

  41. Kimberly Miller says:

    When trying to access the “Static Electricity experiments” link, this message appears: Catchable fatal error: Object of class WP_Error could not be converted to string in /home/auroram42/ on line 69

    Any thoughts on how to get to the experiments (since we are curious about lighting the bulb)?


  42. Aurora says:

    Hi Seva,

    Yes, you can update your username and password to whatever you like in your account, but there’s only one set per account, so you’ll need to decide which ones you want to put on your account. Hope this helps!

  43. Veronica Cable says:

    Aurora, my mom registered me for the summer camp and with the fall program I have to use her username and password. I would like to use my own username and password in order to access this site any time without depending on my mom being around. Can this be done?
    Seva Cable, 9 yrs. old. 🙂

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