The purpose is to determine if there is any effect in the behavior (the movement) of common one-celled organisms when in the presence of a static electromagnetic field.
There has been a great debate over the years as to whether or not magnetism has an effect on living cells. People on one side of the debate believe that living under high-power electric lines causes harmful electromagnetic radiation that damages farmers' crops and is unhealthy for their bodies. The magnetic field created by alternating current traveling through electric power lines is a moving field; the field expands and collapses many times each second. On the other side of the debate are those people who believe that static fields of magnetism (unlike those generated by high-power electric lines) may be beneficial to health. They place magnets on parts of their body to aid in healing various ailments and injuries.
No doubt, you have at some time placed a magnet underneath a piece of paper or cardboard, sprinkled iron filings on top, and tapped it to see a pattern as the filings form lines, showing the otherwise invisible magnetic lines of force.
Magnetism is a phenomenon that is intimately related to electricity. Early scientists realized this when they placed a compass next to a wire through which electricity was flowing. The compass needle was deflected when electricity was flowing in the wire.
When direct current (DC), which is the type of current flow that comes from a battery, travels through a wire, a magnetic field extends out from the wire. Do common
single-celled organisms respond to this field by moving toward or away from the wire?
Hypothesize that several common one-celled organisms will not show any response (to move away from or to move toward the source) to a static electromagnetic field.
- Model train DC transformer
- Small 12-volt light bulb and socket
- Hook-up wire
- Wire cutters
- Small slotted screwdriver
- 40x or 50x microscope
- Microscope slide
- Petroleum jelly
- Adhesive or masking tape
- Live single-celled organisms (euglena, paramecium, flagellum, amoeba, and so forth)
Using hook-up wire, connect a model train DC transformer to a 12-volt light bulb to make a complete circuit. Any variable power supply or DC power transformer is appropriate, including one designed for model HO racing car sets. One piece of wire should be very long, so it can be draped across a slide on a microscope. The train power supply has a variable control on it, so the amount of electricity that flows in the circuit can be changed from zero to its full potential.
Position a microscope slide under the microscope and lay the wire across the slide. Use adhesive or masking tape to secure the wire in place. Be sure the wire is flat against the slide.
In the middle of the slide, squeeze a tube of petroleum jelly to form a "donut-shaped" circle. This will act as a wall to contain a tiny liquid pool of microorganisms. If your petroleum jelly is in a jar, use an ice-pop stick or a toothpick to form the petroleum dam.
From a science supply house or your high school biology teacher, obtain live single-celled microorganisms. They must be active organisms that are able to move on their own. These include euglena, paramecium, flagellum, and amoeba. Place a few small drops of the liquid medium containing the organisms in the "petroleum pool." The petroleum will not harm the organisms.
Set the microscope with a large-enough field of view so the wire and organisms around it can be seen.
Observe the organisms to be sure they are alive and moving around. Turn on the power supply and watch to see if any response occurs by the organisms to the wire that now has an electromagnetic field surrounding it. Try varying the amount of electricity supplied through the wire. The light bulb will give a visual indication that current is flowing, and its dimness or brightness is also a relative gauge indicating the amount of current.
Write down the results of your experiment. Document all observations and data collected.
Come to a conclusion as to whether or not your hypothesis was correct.
- Electromagnetic fields are also present in a wire carrying alternating current (AC). With AC, the electromagnetic field builds and collapses many times each second. Repeat the experiment using AC rather than DC. An AC power supply can be obtained from your local electronics store. An AC doorbell transformer, available at your local hardware store, will also work.
- Increase the magnetic field by exposing single-celled organisms to the strong alternating magnetic field from a bulk tape eraser (available at electronic stores) used to erase audio and video tapes. Observe the organisms.