A resistor with a movable contact that is adjusted by turning a shaft is called a(n) ? resistor.

A resistor with a movable contact that is adjusted by turning a shaft is called a(n) ? resistor.

• A. adjustable
• B. fixed
• C. tapped
• D. variable

Answer: (D)

A resistor with a movable contact adjusted by turning a shaft is a variable resistor. The moving contact (the wiper) slides along the resistive element, so the portion of the total resistance that’s in the circuit changes as you turn the shaft. This lets you tune current or voltage precisely. A potentiometer is a common example of a variable resistor, often with three terminals, while a rheostat uses it as a two-terminal adjustable resistance. The other terms don’t fit as well: a fixed resistor cannot be adjusted, a tapped resistor implies fixed steps, and while adjustable is descriptive, the standard term used in circuits is variable resistor.

A resistor with a movable contact adjusted by turning a shaft is a variable resistor. The moving contact (the wiper) slides along the resistive element, so the portion of the total resistance that’s in the circuit changes as you turn the shaft. This lets you tune current or voltage precisely. A potentiometer is a common example of a variable resistor, often with three terminals, while a rheostat uses it as a two-terminal adjustable resistance. The other terms don’t fit as well: a fixed resistor cannot be adjusted, a tapped resistor implies fixed steps, and while adjustable is descriptive, the standard term used in circuits is variable resistor.