bulk resistance - The natural resistance of a "P" type or "N" type semiconductor material. equivalent resistance - Total resistance of all the individual resistances in a circuit. Four arm bridge circuit used to measure resistance, inductance or capacitance. - insulation resistance - Resistance of insulating material. The greater the insulation resistance, the better the insulation. internal resistance - Every source has some resistance in series with the output current. When current is drawn from the source some power is lost due to the voltage drop across the internal resistance. Usually called output impedance or output resistance.