When three leads are used on a variable resistor, the device is commonly used as a control in a circuit.

When three leads are used on a variable resistor, the device is commonly used as a control in a circuit.

• A. Potentiometer
• B. Rheostat
• C. Regulator
• D. Toggle switch

Answer: (A)

Three leads on a variable resistor identify it as a potentiometer. The key idea is the wiper that slides along the resistive track, letting you sample a portion of the total resistance. When used as a control in a circuit, you typically connect the two fixed ends across a source and take the output from the wiper, creating a voltage divider. This lets you vary the voltage (and thus the signal level) feeding the next stage without drawing much current from the source. If you used only two leads, you’d have a rheostat, which acts as a simple variable resistor to limit current. A regulator maintains a steady output voltage, and a toggle switch is just a mechanical on/off control. That’s why the three-leaded device used as a control is a potentiometer.

Three leads on a variable resistor identify it as a potentiometer. The key idea is the wiper that slides along the resistive track, letting you sample a portion of the total resistance. When used as a control in a circuit, you typically connect the two fixed ends across a source and take the output from the wiper, creating a voltage divider. This lets you vary the voltage (and thus the signal level) feeding the next stage without drawing much current from the source. If you used only two leads, you’d have a rheostat, which acts as a simple variable resistor to limit current. A regulator maintains a steady output voltage, and a toggle switch is just a mechanical on/off control. That’s why the three-leaded device used as a control is a potentiometer.