Where to place an ammeter: to measure the current leaving the second resistor in a four-resistor series circuit, where can the ammeter be inserted without changing the reading?

Introduction / Context:
In a pure series circuit, the same current flows through every element because there is only one path for charge flow. This concept underpins ammeter placement and ensures consistent current readings regardless of location along the loop.

Given Data / Assumptions:

• Four resistors connected in series.
• Goal: measure current leaving the second resistor.
• Assume an ideal ammeter (very low internal resistance) placed in series.

Concept / Approach:

Series circuits have identical current at all points: I1 = I2 = I3 = I4. Hence, inserting an ammeter anywhere in series yields the same current measurement, provided the meter is correctly placed in series (not in parallel) and does not significantly alter the circuit.

Step-by-Step Solution:

Verification / Alternative check:

Kirchhoff’s current law: in a series loop with no branches, current continuity ensures equal current everywhere.

Why Other Options Are Wrong:

Specifying one segment suggests different currents in different segments, which is false for series circuits. All positions yield the same reading.

Common Pitfalls:

Placing an ammeter in parallel (shorting part of the circuit) or assuming current changes between series elements.

Final Answer:

at any point in the circuit