When several resistors are connected in series in an electric circuit, how does the electric current compare at different points along that series branch?

Introduction / Context:

This question is from basic electric circuits. Understanding the behavior of current in series and parallel connections is essential for analysing household wiring, electronic circuits, and many practical devices. In a series connection, components are connected end to end so that the same current flows through each component in the chain.

Given Data / Assumptions:

• Several resistors are connected in series in a single branch of the circuit.
• The circuit is powered by a source such as a battery or power supply.
• We focus on how the current varies along that series branch, not on its overall magnitude compared to a different circuit.

Concept / Approach:

In a series circuit, there is only one path for charge to flow. Because charge cannot pile up at any point in a steady state direct current circuit, the rate of flow of charge, that is, the electric current, must be the same at every cross section along the series path. The total resistance in series is the sum of individual resistances, and this affects the overall magnitude of the current, but the current value itself is identical through each resistor and through the connecting wires in that branch.

Step-by-Step Solution:

Verification / Alternative check:

Using Ohm’s law, for a series combination the total resistance R_total equals R1 + R2 + R3 and so on. The circuit current is I = V / R_total, where V is the applied voltage. Because there is only one branch, the same current I flows through each resistor. Measurements with an ammeter placed at different positions in a simple series circuit confirm that the current reading does not change, provided the circuit remains unchanged and connections are ideal.

Why Other Options Are Wrong:

• The current increases as it passes through each resistor: Resistors oppose current; they do not create additional current.
• The current becomes exactly half after the first resistor: There is no rule that halves current at each resistor in a series circuit.
• The current decreases after each resistor: In an ideal series circuit, current is equal at all points; only voltage drops across each resistor.

Common Pitfalls:

Students sometimes confuse current with voltage. They may think that because voltage drops across each resistor, current must also drop, which is incorrect. In a series circuit, the current is constant, while voltage is divided among components. In parallel circuits, the voltage across each branch is the same, while currents can differ. Keeping these two cases clearly separated helps avoid many basic circuit mistakes.

Final Answer:

In a series circuit, the current remains the same through all the resistors.