It is required to measure angular position. Considering these transducers—(1) circular potentiometer, (2) LVDT, (3) E pick-up, and (4) synchro—which devices are appropriate for angular position measurement?

Introduction / Context:
Choosing the right transducer depends on the physical variable. Angular position is commonly measured using rotary devices that directly sense shaft angle and provide an electrical output proportional to that angle. This question asks you to identify suitable transducers from a mixed list of rotary and linear sensors.

Given Data / Assumptions:

• (1) Circular (rotary) potentiometer: a resistive element with a wiper rotating with the shaft.
• (2) LVDT: Linear Variable Differential Transformer—intended for linear displacement.
• (3) E pick-up: an ambiguous term (often eddy-current or magnetic pick-up) typically suited to speed, proximity, or events, not absolute angle.
• (4) Synchro: a rotary transformer system for angular position/telemetry.

Concept / Approach:
Match sensor physics to the variable: rotary potentiometers and synchros directly produce signals proportional (or convertible) to shaft angle. LVDTs are for linear displacement, and generic E pick-ups usually do not deliver absolute angular position without auxiliary mechanics and signal processing.

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