Of the movie’s many amazing machines (real and imagined), the Jacob’s Ladder is perhaps the most iconic. It consists of two vertical wires, connected by a buzzing electrical arc that slowly travels upward. The science behind a Jacob’s Ladder is simple: When voltage is applied between conductors—in this case, the two wires—electrons on the positive side want to leap to the negative side. To do that, they have to over- come the insulating barrier of air between the wires. If you crank the voltage high enough, the electrons break free and turn the air into plasma. Since plasma is a great conductor of electricity, an arc appears between the wires. The heated air around the plasma is less dense than the air above, so it moves upward. The electrons follow, causing the arc to travel. The effect makes for a spectacular movie prop—and an even more impressive garage attraction.
WARNING: Use in a well-ventilated area. Never touch or go within a foot of the electrodes when the transformer is plugged in—it could cause injury or death.
Stats:
Time: 4 hoursCost: $125Difficulty: Easy to medium
Tools:
ScrewdriverSoldering iron
Materials:
9,000- to 15,000-volt neon-sign transformerThree-position terminal stripNo. 10 terminal screwsPlywood board, 24-inch-by-12-inch-by-1⁄2-inchTwo 14-inch-long No. 10 bare copper wiresTwo 1-megaohm resistors16-gauge insulated wire1-inch-long No. 10 bolt with screw head cut off22-quart clear polycarbonate container
Instructions:
This article was originally published in the March/April 2016 issue of Popular Science, under the title “Unleash Your Inner Mad Scientist with a Jacob’s Ladder.”
