Abstract: The electric field of a parallel plate condenser of polar plate with straight gap is studied by using the Schwarz-Christoffel transformation in the coordinate system of the complex number, and its electric potential distri- bution and electric intensity distribution are obtained. In further, the influence of a polar plane with straight gap on capacity of supporting voltage and capacitance is discussed.

Key words: parallel plate condenser, straight gap, Schwarz-Christoffel transformation, capacity of supporting voltage, capacitance