Which device is designed to be set with a screwdriver and then left without further adjustment?

Which device is designed to be set with a screwdriver and then left without further adjustment?

• A. Preset variable resistor
• B. Rheostat
• C. Potentiometer
• D. Diode

Answer: (A)

The device designed to be set with a screwdriver and then left alone is a preset variable resistor, also known as a trim potentiometer. It includes a small adjustment screw on top that changes the resistance when turned with a screwdriver. Once the desired resistance is set, the component is intended to stay fixed for calibration or tuning purposes, rather than being continually adjusted by the user. This fits because presets are specifically made for precise, one-time or infrequent adjustments during setup, not for routine control. In contrast, a rheostat and a potentiometer are typically adjusted by turning a knob or slider to continuously vary resistance or voltage, and a diode provides a fixed or non-adjustable electrical behavior.

The device designed to be set with a screwdriver and then left alone is a preset variable resistor, also known as a trim potentiometer. It includes a small adjustment screw on top that changes the resistance when turned with a screwdriver. Once the desired resistance is set, the component is intended to stay fixed for calibration or tuning purposes, rather than being continually adjusted by the user.

This fits because presets are specifically made for precise, one-time or infrequent adjustments during setup, not for routine control. In contrast, a rheostat and a potentiometer are typically adjusted by turning a knob or slider to continuously vary resistance or voltage, and a diode provides a fixed or non-adjustable electrical behavior.