Electric field converter
Convert field strength between V/m, kV/m and V/cm, and see how close your value is to making air conduct.
That's 2× as strong as near an appliance, while under a power line is 5× stronger. Across a 1 mm gap that would need about 1 V.
What it means
How strong is that field?
Air breaks down around 3 MV/m in dry conditions. Humidity, sharp points and dust all lower that figure.
Every unit
Your field in every unit
Learn
Three things worth knowing
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Volts divided by the gap
Field is simply voltage over distance. That is why a tiny gap with modest voltage still sparks: shrink the distance and the field soars.
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Faraday’s lines of force
Faraday pictured invisible lines stretching between charges; Maxwell turned that picture into equations. Field strength counts how tightly those lines are packed.
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Field is not voltage
A 400 kV power line has a modest field at ground level because the ground is far away. It is the gradient, not the number on the pylon, that matters.
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Background
About electric field units
Electric field strength is volts across a distance: V/m. Two plates 1 mm apart at 1,000 V sit in a field of 1 MV/m, which is a third of the way to a spark.