Here is a very simple electromagnetism experiment that can be performed with ordinary material such as nails, enamelled wires, pieces of tin etc. Because of its simplicity, it is a great job for science fairs in schools or STEMers.
The design is simple and its effect well visible: when we tighten the pressure switch a blade is drawn, throwing away a ball of paper, styrofoam or even a grain of beans.
The apparatus functions as both an "electromagnetic shooter" as demonstrating the effect of electromagnetism,
The experience in the case of a school work should be accompanied by explanations on the magnetic effect of electric current, which can be summarized as follows.
Operation principle
An electric current, when circulating by a wire, creates in its turn a magnetic field. We can reinforce this magnetic field by winding the wire in the form of a coil.
In this way, the field is concentrated inside the coil which, if it contains a ferrous material such as a nail, magnetizes it, transforming it into a magnet.
The attraction capacity of this magnet will depend only on the electric current, which means that it only attracts objects while there is current flowing.
When the current is interrupted, the magnet loses all its capacity of attraction.
By placing a metal blade nearby, it can be attracted strongly when we set the current and, with that, throw away a styrofoam ball.
ASSEMBLY
In figure 1 we have the diagram of the apparatus.
In figure 2 we have the actual appearance of the assembly.
In the nail we rolled of 200 to 500 turns of fine enamelled wire. The holder for the magnet is made of cardboard and the blade is a piece of ordinary canned cut into strip and then folded into the shape indicated in the drawing.
Note the presence of a small gap of 2 to 3mm between the blade and the nail head.
This space is important so that there may be your movement at the time of attraction.
For welding the enameled electromagnet (nail) wires into the cell and switch your tips should be well scraped.
OPERATION
By pressing the pressure switch the blade should buckle by tapping on the nail head. A ball placed in the indicated position should be tossed away.
If there is no force on the movement or the blade is not attracted enough, move it closer to the nail, or wind the bobbin back on the nail with more twists and turns.
If there is still no attraction, check that the enamelled wire is well scraped at the welding point.
Note: Do not leave the switch pressed for more than a few seconds, as the electromagnet may heater and the battery (s) may wear out quickly.
MATERIAL LIST
X1 - electromagnet on nail - see text
B1 - 1.5 to 6V - 1 to 4 large cells
S1 – push button
Various: base of wood, nail, enamelled wire, cardboard, Iatinha, etc.
