In this experiment we will magically force electrons from Scotch Tape to pass to and from a table (note - we'd use Dad in this experiment but you know how stingy Dad is with things like, Ohhh, his tools for instance. So if you think Dad's stingy with tools try asking him if you can transfer some of his electrons...). Of course, you won't be able to actually see the electrons transfer but you will definitely see the affects of the hopping electrons. The device we will create can further be used to test the charge of any object you want.
- Fill the 2 film cans about 3/4 full of clay.
- Place 2 straws, side by side, in each of the film cans. Push the straws down into the clay.
- Bend the flexible ends of the straw so they are horizontal (parallel to the table you are working on).
- Position the straws, by twisting them, so that the horizontal arms of the straw face away from each other in opposite directions (it'll look sort of like a TV antenna or the letter 'T'). Make sure the arms are the same height.
- Tear off two 3-4 inch pieces of tape. Press them onto a flat table. Place them near the edge of the table so that a small piece of the tape is available to use as a 'handle'.
- Grab the 'handle' of the tape and quickly rip it off of the table.
- Stick a piece of the tape onto the 'arm' of one of the straws so that the tape dangles downward off of the extended straw arm. Now place the other piece of tape in the same manner, onto one of the straws in the second film canister.
- At this point you should have 2 film cans, each with two straws sticking up, horizontal arms extended in opposite directions (sort of looks like the letter 'T'). One of the straws in each container should have a small piece of tape stuck to the 'T', and hanging downward.
- Now, place the cans next to each other, about 6 inches apart. Move and turn the cans so that the pieces of tape become close together with their flat sides facing each other.
See how the tapes repel each other. At this point, both pieces of tape are 'charged' with the same type of charge (either positive or negative depending upon the surface of the table you used). Like charges will repel each other. This charge occurred due to the jumping of negative charges, or electrons, from the tape to the table. The tape actually lost electrons and the table gained them.
- Now tear off 2 more pieces of tape. Press the sticky side of one piece of tape to the smooth side of the other. Leave a small piece of one of the tapes sticking out so that it is available as a 'handle'.
- Now quickly rip the pieces of tape apart and stick them to the two remaining arms.
- Move and turn the cans to bring these 2 arms (with the pieces of tape we just stuck on them) close together.
Notice how these pieces of tape attract each other. Same principle as above. When your ripped the tapes apart, electrons actually jumped from one piece of tape to the other. One piece of tape is now positively charged and the other negatively charged. And remember, opposite charges attract each other.
- Run a comb through your hair a few times.
- Place it next to each of the pieces of tape. Notice which ones it repels and which ones it attracts.
See how the comb acts with each piece of tape. Remember the two pieces of tape that we stuck together? The one that was stuck on its sticky side should attract to the comb. The comb will repel the one that was stuck on the smooth side. In this case the comb is negatively charged.
Strangely enough, the other two pieces of tape (that we ripped off of the table top) will react differently depending upon the type of table you used in the experiment. Some plastic types of table cause the tapes to repel (indicating that the tape has a negative charge) and other types of table surfaces will cause an attraction (indicating that the tape has a positive charge).
These charges are a result of the electrons jumping from one object to the other. One object actually loses electrons and the other gains them. They can pass from the table to the tape or from tape to tape. This concept is the basis for many well known phenomenon such as lightening, static electricity and magnetism.
Now you can test the charges of various objects using these new devices. All you have to know is the charge of the piece of tape you are using and remember that opposite charges attract and like charges repel. You can use the comb to test the charges of each piece of tape since the comb will always be negatively charged. One little tip though - the charges will slowly leak away so they must periodically be recharged by sticking them back together and ripping them apart again.
Parent/Teacher/Advanced Notes [click to expand]
Your child may notice that their hand actually attracts all of the pieces of tape. This is because the human body is uncharged. An uncharged object will attract any charged object, regardless of their charge.
We've talked quite a bit about electrons. A electron is a negatively charged subatomic particle. A useful model of an atom portrays it as a tiny nucleus surrounded by electrons. The electrons are at various distances from the nucleus and are arranged in energy levels called shells. Electrons occupy almost the entire volume of an atom, but electrons themselves account for only a small fraction of an atom's mass. The chemical behavior of an atom is determined largely by the number of electrons in its outermost shell. When atoms combine and form molecules, electrons in the outermost shell are either transferred from one atom to another or shared between atoms.
Ordinarily, an atom has an equal number of electrons and protons, positively charged particles found in the nucleus. Each electron carries one unit of negative charge, and each proton carries one unit of positive charge. As a result, the atom is electrically neutral. If an atom gains electrons, it becomes negatively charged. If it loses electrons, it becomes positively charged. Electrically charged atoms are called ions.
Electrons are fundamental units of matter--that is, they are not made up of smaller units. The diameter of an electron is less than 1/1,000 the diameter of a proton. The mass of an electron in grams may be written with a decimal point followed by 27 zeros and a 9. Electrons are the lightest particles that have an electric charge.
Share your knowledge
Let Reeko know how you rate this experiment
Little Scientist rating [Avg: 3 from 6 votes]
...or tell your friends about it!