This Jacob’s bi ladder impossibly seems to be going DOWN as well as up. But how can that be?
“Continue reading” for more details, video and photo.
A normal Jacob’s ladder is a high voltage device where a spark jumps between two rods that diverge at the top. The spark jumps across at the shortest point at the bottom. Hot air from the spark rises and the spark follows, becoming ever longer before it finally “breaks” at the top.
Hence a Jacob’s ladder requires hot non-turbulent air to rise. There is a definite up and down and they won’t work upside down.
This specially constructed ladder uses a long central rod which can rotate to widen the gap. It was run from my 80 kV DC supply. The normal upper segment works by the usual heated air mechanism. The lower segment is magnetically driven and has the North poles of three 1 inch NIB magnets just behind the red acrylic. The magnetic effect overrides the hot air one. The current has to be in the right direction for the magnetic field or it won’t work.
The photo above shows the concealed NIB magnets behind the red acrylic. Left electrode is positive and North poles are closest.
However, after some thought I realize that there is another way to achieve an identical photo without magnets. You need this setup in a box containing the camera which are all free to be rotated so they are upside down. If the ladder is rewired so the sparks are between the central electrode and the uppermost outer electrode, then a long exposure with one rotation through 180 degrees (switching to the upper electrode when it rotates), will give a good result.
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Photo Date: November 4, 2007