Which formula is used to find the total resistance of a DC parallel circuit with three different resistances?

The correct formula to find the total resistance in a DC parallel circuit is the one that states that the inverse of the total resistance (R) is equal to the sum of the inverses of the individual resistances (R1, R2, and R3). This relationship is derived from Ohm's law and the properties of resistors in parallel, where the voltage across all resistors is the same, and the total current is the sum of the currents through each resistor.

In a parallel circuit, the formula R = 1 / (1/R1 + 1/R2 + 1/R3) reflects that as more resistors are added in parallel, the total resistance decreases. Each additional pathway for current effectively reduces the overall resistance because there are more routes for the current to flow through. Hence, the more resistors you have in parallel, the lower the total resistance becomes compared to any individual resistor in the circuit.

The other options represent different configurations. The formula R = R1 + R2 + R3 is applicable to series circuits, where resistances add together directly. The product formula (R = R1 * R2 * R3) does not apply to parallel circuits. Meanwhile, averaging the resistances (R =