Thermocouple construction basics: all thermocouples used for temperature measurement rely on dissimilar metal __________ to generate a thermoelectric voltage.

Introduction / Context:
Thermocouples are among the most common industrial temperature sensors. They harness the Seebeck effect: a voltage is produced in a loop made of two dissimilar conductors when their junctions are at different temperatures. Recognizing the essential construction element helps avoid misconceptions about form factor vs. function.

Given Data / Assumptions:

• We focus on the dissimilar-material requirement, not the geometry of the protective sheath.
• Common types include K, J, T, S, R, B, and N, each defined by specific wire alloys.

Concept / Approach:
The fundamental element is two wires (or conductors) of different alloys joined at a measuring junction, with the other ends forming the reference. While these wires may be formed into strips, foils, or small beads for specialized applications, the canonical and most widespread construction is with wires. The dissimilarity is what matters: identical metals would not develop a net Seebeck voltage in a closed loop when junctions are at different temperatures.

Step-by-Step Solution:
Identify the active components: two dissimilar conductors.Realize most practical thermocouples are made from standardized wires.Select “wires” as the correct completion.

Verification / Alternative check:
Standards (IEC 60584, ANSI) specify thermocouple wire compositions and tolerances, reflecting wire-based construction as the norm.

Why Other Options Are Wrong:
Strips/bars/foils/beads: Possible shapes, but the key is dissimilar wires in standard instrumentation; identical metals would not produce the needed EMF.

Common Pitfalls:
Confusing the protective sheath or ceramic insulators with the active thermoelectric elements; only the dissimilar metal conductors create the signal.

Final Answer:
Wires