SCIENCE GIZMOS: Energy Ball
This science gizmo Energy Ball now has upgraded electronics, and a pull tab to preserve battery life. It is a great way to demonstrate for kids how to conduct electricity in a circuit. The energy ball contains 2 small metal electrodes that, when touched simultaneously, cause it to light up. Comes with a Teacher’s Guide. No other energy ball on the market with these upgraded features. (NOTE: Brand may vary from image displayed)
A resistance touch switch requires two electrodes to be in physical contact with something electrically conducting (such as a finger) in order to function. They function by decreasing the resistance between two metal pieces. Thus, its construction is significantly easier than that of the capacitance switch. By placing one or two fingers across the plates, the switch can be turned on or off. When the finger(s) are removed from the metal pieces, the gadget is turned off.
The base of the first transistor would be connected to one of the electrodes in one version of a resistance touch switch involving two Darlington-paired transistors. Also usable is an N-Channel, enhancement-mode, metal oxide field effect transistor. Its gate can be connected to one of the electrodes and the other electrode through a positive voltage and a resistance, respectively.