How is total resistance calculated for a parallel circuit?

The calculation of total resistance in a parallel circuit is based on the principle that the total current entering the circuit is equal to the sum of the currents through each parallel branch, and that the voltage across each branch remains the same. The correct formula to determine total resistance in a parallel circuit is derived from the relationship between voltage, current, and resistance, specifically Ohm's Law.

In a parallel circuit, instead of summing the resistances directly, the inverse of each individual resistance is taken. This is because when resistors are placed in parallel, the overall resistance decreases. The formula indicates that 1/R(total) is equal to the sum of the inverses of each individual resistance, allowing for the calculation of total resistance in the circuit:

1/R(total) = 1/R(1) + 1/R(2) + 1/R(3)

By inverting this formula, the total resistance can be found effectively. Therefore, the established method to find total resistance for multiple resistors in parallel is to use the reciprocal formula provided.

The other options describe methods for calculating resistance in different contexts, such as series circuits or using Ohm's Law inappropriately. For instance, Option A relates to calculating current or voltage rather than resistance