Household Repairs Note. For a flashlight to work, electric current must flow from the positive terminal (the small brass button) of the battery to the filament and back to the negative terminal (the zinc bottom) of the battery. In a tubular flashlight the current flows from the brass button of the top battery to the bottom of the bulb, through the filament, then out through the screw base of the bulb to the reflector, then to a metal strip attached to the bottom of the turn-on switch, then to the coiled spring in the base of the flashlight and finally to the zinc base of the bottom battery. For the circuit to be complete, the batteries must be arranged so that the brass button of the bottom battery touches the zinc base of the one next nearest the light; the brass button of the top battery must touch the base of the lamp; the metal strip on the bottom of the switch must touch the reflector; and the spring in the base of the flashlight must touch the zinc base of the bottom battery.

In an electric lantern the circuit is completed in the same way, but in this case the positive and negative terminals of the large square battery are close together on top of the battery. They make contact with the bulb and switch by an arrangement of metal strips which are readily located when the lantern case is opened.




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May 22, 2012