Electronics Engineering (ELEX) Board Practice Exam 2025 - Free ELEX Exam Practice Questions and Study Guide

In a parallel circuit, the total resistance is calculated using the formula where the reciprocals of the individual resistances are summed. This leads to a relationship where the total resistance is inversely proportional to the sum of the reciprocals of each resistor in the circuit. The formula highlights that as resistors are added in parallel, the overall conductance increases, which decreases the total resistance.

This approach is rooted in how current divides among the various paths; in a parallel arrangement, each path (resistor) allows the current to flow independently. Therefore, even if there are several resistive paths, the total resistance of the circuit is always less than the resistance of the smallest individual path. The formula provided effectively captures this behavior from both theoretical and practical perspectives.

The other options present inaccuracies or refer to different circuit configurations. The first option only applies to series circuits where resistances simply add up, while the third option describes Ohm's law (voltage divided by current), which isn't specific to calculating total resistance in parallel circuits. The fourth option provides a formula related to just two resistors in parallel, which is not applicable when considering multiple resistors. Understanding the correct formula for calculating total resistance in parallel circuits is essential for designing and analyzing electronic circuits.