Component identification in circuits: The sliding contact used to adjust resistance in a variable resistor is called the wiper of which device?

Introduction / Context:
Variable resistors are ubiquitous in electronics for adjusting levels such as volume, bias, or reference voltages. Recognizing the parts of these devices helps in wiring and troubleshooting. The movable contact that changes the division of resistance is universally called a 'wiper.'

Given Data / Assumptions:

• A 'sliding contact' is mentioned, which implies mechanical adjustment across a resistive track.

Concept / Approach:
A potentiometer is a three-terminal variable resistor. The end terminals connect across the entire resistive element; the center terminal is the wiper, which slides over the resistive track to tap a variable fraction of the total resistance, creating an adjustable output voltage or resistance depending on configuration (voltage divider or rheostat mode).

Step-by-Step Reasoning:

Verification / Alternative check:
Datasheets and schematics label the middle pin of a pot as the wiper. Rotational (knob-type) or linear sliders both use the wiper terminology consistently across manufacturers.

Why Other Options Are Wrong:

• Switch: Changes connectivity, not via a sliding resistive contact.
• Photoconductive cell: Light-dependent resistor; no mechanical slide.
• Thermistor: Temperature-dependent resistor; no wiper mechanism.

Common Pitfalls:

• Confusing a two-terminal variable resistor (rheostat connection) with a fixed resistor; the presence of a wiper indicates potentiometer-style construction.

Final Answer:
potentiometer