Which of the following statements is NOT true about resistors connected in parallel?

RRB Nsg. Superintendent -29 April-2025 (shift-2nd)

General Knowledge

Easy

Appeared in: RRB Nsg. Superintendent -29 April-2025 (shift-2nd)

Explanation

In a parallel circuit, the total current from the source divides among the different paths or branches.
According to Ohm's Law (I = V/R), the current in each branch is inversely proportional to the resistance of that branch.
Therefore, the current will only be the same if all resistors have identical resistance values; otherwise, it will be different for each resistor.
This makes the statement that the current is the same through each resistor incorrect.

Option B: This statement is a true property of parallel circuits. It represents the mathematical formula for calculating the total equivalent resistance.
Option C: This statement is a true property of parallel circuits. Adding more parallel paths for current always decreases the total opposition to the flow.
Option D: This statement is a true and defining property of parallel circuits. All components in parallel are connected across the same two points, so they must have the same voltage drop across them.

Visual 1: Circuit Diagram - A diagram showing three resistors (R₁, R₂, R₃) connected in parallel to a voltage source (V). The diagram should illustrate how the total current (I_total) from the source splits into I₁, I₂, and I₃ through each respective resistor.
Visual 2: Analogy Diagram - An analogy using water pipes. A large main pipe (representing total current) splits into several smaller parallel pipes (representing branches). This visually explains how the water flow (current) divides, while the water pressure (voltage) remains the same across the openings of all the smaller pipes.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Properties of Resistors in a Parallel Circuit as background academic context rather than a clinical decision trigger.
Understanding basic electrical circuits is foundational for nurses to safely operate and troubleshoot medical equipment like ECG machines, infusion pumps, and defibrillators, all of which rely on these principles.
Knowledge of parallel circuits helps in understanding why plugging too many high-power devices into a single outlet strip (which is wired in parallel) can overload the circuit, trip a breaker, and create a fire hazard in a clinical setting.
What if? If the resistors were connected in series instead of parallel, the current through each resistor would indeed be the same, but the voltage from the source would be divided among them. The total resistance would be the simple sum of the individual resistances (R_total = R₁ + R₂ + ...).

How to Approach the Question

First, identify the core concept: the question asks for an incorrect statement about resistors in a parallel circuit. The keyword 'NOT' is critical and means you are looking for the false option.
Recall the three main rules for parallel circuits: 1. Voltage is the same across all branches. 2. Total current is the sum of the currents in each branch (I_total = I₁ + I₂ + ...), where individual currents depend on resistance. 3. The reciprocal of total resistance is the sum of the reciprocals of individual resistances.
Evaluate each option against these rules.
Option A states the current is the same. This contradicts the rule that current divides based on resistance. This is likely the incorrect statement and thus the correct answer.
Option D states the voltage is the same. This matches the primary rule of parallel circuits, so it is a true statement.
Options B and C describe the rules for calculating and understanding total resistance in a parallel circuit. Both are correct, true statements.

Concept Tested & Keywords

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