Rheostat construction and components: In basic electronics, a rheostat (a two-terminal variable resistor used for current control) comprises which fundamental parts?

Introduction / Context:
A rheostat is a variable resistor typically used to control current in circuits such as dimmers, heaters, and test setups. Understanding its internal parts helps technicians diagnose faults (e.g., noisy adjustment, open track) and choose appropriate components for power handling and resolution.

Given Data / Assumptions:

• The device discussed is a two-terminal variable resistor used primarily for current control (rheostat mode), not a three-terminal potentiometer in divider mode.
• Standard mechanical construction with a resistive element and a movable contact.
• No special multi-gang or digital control features assumed.

Concept / Approach:

A rheostat varies resistance by sliding a movable contact called the wiper along a resistive element (track). The effective resistance between the wiper and one fixed terminal changes with position. In high-power designs, the track is often wirewound on a ceramic former for heat dissipation and robustness.

Step-by-Step Solution:

Verification / Alternative check:

Exploded drawings and datasheets consistently show a resistive element plus a wiper assembly. Potentiometers add a third terminal (the other end of the track) for divider operation, but the physical parts remain wiper + track.

Why Other Options Are Wrong:

• Solenoid and armature: those are electromechanical actuator parts, not rheostat internals.
• Contact and wire wound: incomplete—missing the essential concept of a wiper sliding on a track (not just “contact”).
• Center tap and wiper: a center tap is not a standard rheostat feature.
• Rotor and stator: motor terminology, not applicable here.

Common Pitfalls:

• Confusing potentiometers (three-terminal) with rheostats (two-terminal usage).
• Assuming all rheostats are carbon; many are wirewound for power.

Final Answer:

wiper and resistor track