Bridlewood Electromagnetic Fields (EMFs) Information Service
EMF Science Projects
The following is our first EMF Science Project. If you have other EMF science projects or information on EMF science projects we would very much appreciate being able to present them here (or links to them).
An EMF Science Project to Demonstrate Net Current Controls
Contibuted by Edward Maxey, M.D., F.A.C.S.
Please exercise caution when working with electricity. If you need assistance with this project you may contact Ed Maxey at firstname.lastname@example.org.
The kitchen science project requires:
- a toaster
- two polarized household extension cords (they will plug into an electric outlet only one way)
- one jumper plug
- a clamp on ammeter
- Note: almost all electrical service men have clamp on ammeters. Students should be able to borrow one for their experiments.
- a laminated silicon steel core
- Note: the core from an old audio amplifier power transformer will do. Such cores should be readily available at almost any radio/electronic repair shop.
As set up the above images show:
- Extension cord A is plugged into an outlet, wrapped 11 turns about a laminated silicon steel core and has the jumper connecting its neutral to the neutral of extension cord B.
- If you are using the core from an old audio amplifier power transformer, unless the core is large (desirable) one must cut the male plug from the extension cord, wind the core and then splice the plug back together being very careful to re-attach neutral to neutral and hot to hot (see Figure 3). A core so constructed behaves exactly as does the laminated silicon steel core which is depicted in Figures 1 & 2.
- Extension cord B is plugged into an outlet, has the clamp on ammeter placed about it and has its neutral connected to the neutral of cord A with the jumper plug.
- The jumper plug connects only the neutrals of the two extension cords.
- The toaster is plugged into either of the extension cords.
Net current controls such as this, if widely deployed on the WYE distribution systems used in the United States and Canada, would eliminate 95% of the 60 Hz magnetic fields to which our populations are exposed.
- Turn on the toaster and observe the amperage registered by the clamp on ammeter. It will show zero amperes.
- Move the clamp on ammeter to cord A and again note the amperage. It will register the same as in cord B.
- Turn the toaster off, unplug cord A from the electrical outlet, unwind it from about the laminated steel core and again plug it into the electric outlet as before.
- Turn on the toaster and observe the amperage registered by the clamp on ammeter. It will show half the current required to heat the toaster elements.
- Move the clamp on ammeter to cord A and again note the amperage. It will regester the same as in cord B. This is because half of the current is now returning on each of the two extension cords.
- Conclusion: The net current control (eleven turns about a laminated steel core) causes supply and return currents to balance along the path to which the control is applied even though alternate return paths are available.
REVISED NOVEMBER 1998