In the electric Discharge machining the bubble grows at the electric discharge point. This bubble consumes part of the electric discharge energy.
We have calculated the percentage of the distributed energy, under the condition that the distributed energy is given by radiation and the bubble is a hemisphere.
Our calculation shows that in proportion as the electric discharge duration becomes shorter, the distributed energy and the gas pressure of the bubble become greater, and that a sudden change is to be seen This result agrees with the experiments.