Eddy Current Discs

The exhibit demonstrates the interaction between the magnetic fields of the aluminum discs and those of the permanent magnet which causes the discs to rotate. The middle disc has no gaps and rotates faster than the other two. It has a strong magnetic field because the eddy currents are interrupted and therefore much stronger than the disc with gaps.

Ferro Fluid

In this exhibit, we rotated the disc to move the magnet attached to it and we observed the black fluid on the pan.
The black fluid is Ferro fluid. This liquid is a colloidal mixture of small magnetic particles suspended in a liquid carrier. Ferrofluid becomes strongly polarized in the presence of a magnetic field. When the magnet is moved out of the pan, ferrofluid is dragged up to the side of the container.

Finger Tingler

When we rotate the crank, electricity is produced as indicated by the movement of the voltmeter needle. When someone placed a finger on a brass plate then rotate the crank, it felt nothing in he’s finger. But when someone placed two fingers on the two brass plates and then rotates the crank, there’s a tingling feeling or mild electric shock in the fingers. This indicates that electricity flows through the finger as in a closed circuit.

Flashing Pendulum

The pendulum bob has a magnet at the end. On each swing, the magnet crosses a coil of copper wire assembly. The LED (light emitting diode) bulbs light up as the magnet passes the coil.
The exhibit demonstrates the phenomenon of inducing a current by changing the magnetic field in a coil of wire. This phenomenon called Electromagnetic Induction is the basis for the design of all electric generators.

Floating in Aluminum

In this exhibit, we raised and lower the lifting magnet to make the small magnet float between the two aluminum slabs. We tried to keep the magnet floating between the slabs by adjusting the lifting magnet.
We noticed that the closer the magnet is to the aluminum, the slower it moves. As we draw the lower magnet up with the upper magnet, the motion includes eddy currents that slow down the lower magnet’s motion. This effectively sets up a feedback system slow enough for us to keep the magnet suspended in mid-air.

Following Faces

We stood from a distance and looked at the faces. We walked to the left and to the right as we looked at the faces. We also lowered and raised our body while looking at the faces. The face is a concave translucent mask. Our eye-brain system has learned that faces are usually convex, that is, curved outward rather than concave. When we walked, the face seemed to turn and follow us wherever we went. When we moved up & down, the face also seems to nod. This makes the entire face appear to be following us.

Frozen Shadow

While roaming around the displays, we ended up on a small, dark room covered with black curtains. We found out that that exhibit is called "FROZEN SHADOW". We were familiar with this one because we also saw it on our previous science fair. Many students were entertained by this one. Some even gotten into arguements if who will try first.

This exhibit is fun because of it's special effect. Someone pressed the button and we went near the wall. We made a funny pose while waiting for the flash and then stepped away from the wall. And then, do you know what happened?

Our shadow was still on the wall. That was very interesting for us. The wall is painted using glow-in-the-dark pigments and white paint binder. The pigments or phosphors absorb light and continue to glow for 2 to 3 minutes even after the light switches off.