Archive Index ... Column Index
By: Beth Bemis
Join Explorit Science Center for an electrifying Saturday! On March 1, from 1:30-4:00 p.m., Kin Yan, a graduate student in electrical engineering at UC Davis and one of Explorit's staff members, will dazzle visitors with the Van de Graaff generator.
The Van de Graaff generator is an electrostatic machine. A rubber belt passes over a cloth pulley in the base so that electrons become separated from the pulley and are carried off by the rubber belt. In the top of the generator, a metal brush collects the electrons and passes them to a metal sphere.
These "extra" electrons on the sphere repel each other so that some of them are pushed through your hands to your body, if you are touching the metal sphere. All parts of your body become electrically charged. Since the electrons want to get as far away from each other as possible, they will travel along your hair, causing the strands of hair to "stand on end."
With adult supervision and staff knowledge of the Van de Graaff generator, this is an excellent opportunity to investigate the wonders of static electricity. You can also explore the interaction between electricity and magnetism in "The Power Pair," Explorit's current exhibition which will run through April 6.
Explorit Science Center is located at 3141 5th Street in East Davis. Public hours are Saturday from 11 a.m. to 4:30 p.m., Sunday from 1:00 to 4:30 p.m., and Tuesday through Friday from 2:00 to 4:30 p.m. Admission is $3; members, teachers, and children under 4 are free. For more information, call Explorit at 756-0191.
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Did you know that you are electric?! Maybe you want to check out the chemistry between you and a friend? Perhaps you want to get a feel for group dynamics? Try your hand at Explorit with the human battery!
A battery is a device that uses chemistry to produce electrical potential energy. The essential ingredients in a battery are the electrodes. These are made from two different materials which are chemically active. Electrodes connected by a wire can form a circuit in an electrolyte, a small particle which can conduct a charge, but where does the energy come from?
Chemical reactions occur when electrodes enter an electrolytic solution. The type of chemical reaction depends on the electrodes and the type of cell of the battery, but the reaction causes electrons to be released as positive and negative ions. Movement of these particles away from similarly charged ions creates a current.
When you place your hands on the people battery, the salt in the sweat on your hands causes two different chemical reactions on the metal plates. The imbalance of electrons creates the potential for a current. Your body acts as a conductor for the current, and that current registers on the meter.
Your body is the site of a large number of electrical events all the time. The beating of your heart, the blinking of an eye, or even reading this column depends on electrical signals in your brain and throughout your nervous and muscular system. Those signals depend on the appropriate balance of electrolytes inside your body.
The electrical signals are called nerve impulses, or action potentials. An action potential is the temporary change in the ion balance between the inside and outside of a nerve cell. This change in ions creates an electrical signal which travels along the nerve cell causing the release of chemicals which signal the next nerve cell.
The production of an action potential depends on the flow of sodium and potassium ions across the cell membrane. These ions carry electrical charges; they are electrolytes. Imbalances of these electrolytes can cause misfiring of the nerve cells, known as neurons. To keep your electrolytes balanced, it is important to stay properly hydrated. So grab a large drink of water and see if you can get current with the person battery!
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After you've charged yourself up with "The Power Pair: Electricity and Magnetism," step into the Discovery Den and see what you can find in the Putah Creek pond water aquarium. Not only are there lots of tiny critters to look for under the microscope, there are some macroscopic surprises!
There are two new crayfish residents to see. These almost clear-bodied little fellas are exploring their new environs. Look for them in the sunken cup. And, if you're really observant, you might come across the dragonfly nymph. It likes to dig under the dirt, so look carefully. We'll keep you updated on the new and exciting changes within the "living lab."