TITLE: What makes Jacob's ladder spark to go upwards?
QUESTION [1 upvotes]: In a Jacob's ladder (https://www.youtube.com/watch?v=GaC4BnbH1NY&index=3&list=PL_SAbPKia2YMFi-t8z5WFYCd86Plcs1Un) a spark is originated in the bottom and climbs up to the top.
I have read in several places that what makes the spark to go upwards is the heating of the air. I wonder if it could not also be attributed to the magnetic force generated by the currents across the conductors.
What would happen if we put the ladder upside down? Would the spark go upwards or downwards?

REPLY [1 votes]: We just put Jacob's Ladder Upside down and the spark DID NOT go up. So it tells us that the magnetic field doesn't play a significant role in this experiment: https://youtu.be/eOyk8j2ertU. It is hot air moving up (convection of air) and not the magnetic force.
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