Electronics Engineering (ELEX) Board Practice Exam

What happens to the voltage across each resistor in a network when the values of all the resistors are doubled?

1. Increases to twice its original value

2. Decreases to half its original value

3. Remains the same

4. Depends on the total resistance

The correct answer is: Remains the same

When the values of all resistors in a network are doubled, the voltage across each resistor remains the same due to Ohm's Law, which states that the voltage (V) across a resistor is equal to the current (I) through it multiplied by the resistance (R), or V = I * R. If all resistances are doubled, the total resistance in the circuit changes accordingly. However, if we consider a simple circuit configuration, such as a series or parallel arrangement, the behavior of voltage in relation to current and resistance can remain stable under certain conditions. In a series circuit, while doubling the resistance will affect the total current flowing through the circuit, the voltage drop across any individual resistor remains consistent relative to the voltage source applied as long as the source voltage doesn’t change. In a parallel circuit, the voltage across each resistor is equal to the source voltage, and since the source voltage remains constant, doubling the resistors does not change the voltage across them. Thus, regardless of the configuration (series or parallel), the voltage across each resistor will not change when all the resistors' values are doubled, which leads to the conclusion that it remains the same. This makes the correct answer appropriate based on the fundamental principles of circuit