First done for Discovery Channel. It used 10 kJ from the capacitor bank to explode a thin (15 thou) iron wire inside a watermelon.
“Continue reading” for more details and photos.
Each photo in the exploding watermelon animated sequence above is taken at 5 frames per second i.e. 0.2 seconds apart. I am covering my face with an acrylic plate and am pulling the string to trigger the big spring loaded switch. I have looped it around the fence as the string had got wet hence conductive to the 10 kV I was using. You have to be very alert re safety, particularly when circumstances like filming disrupt your routine.
The first shot above shows the moment just after power is applied and it is likely the capacitors have dissipated all their charge already. The iron wire has melted and tiny droplets of liquid iron (the orange spray) have sprayed out the ends along with a puff of grey smoke. Note that an AK47 bullet has about 2kJ of energy and the power used here is 10 kJ.
The fine iron wire is soldered on to a thin steel rod which is pushed through the watermelon then cut off. The connection looks dodgy for 100 kA doesn’t it. It really just needs to be the seed for a lightning like bolt to form which will dissipate the energy within the exploding watermelon as a sudden pressure wave.
This has become a favourite for performances and TV. It must still be treated with respect however.
Haro from German TV has a turn.
A night time shot from my Open Day 2010
On a recent 2013 TV shoot, watermelon juice from a previous shot leaked and caused a short circuit and a premature explosion. It was all caught on film while the presenter (Heri from ITL TV Germany) was talking in front of it. Certainly gave him a start.
Related pages
Exploding Hot DogTry something else
Antique homemade printer plotter
External links
Exploding watermelon – spontaneous
Photo Date: 2007, 2013