Which resistor type is primarily used to adjust current in a circuit such as lamp brightness or motor speed?

Which resistor type is primarily used to adjust current in a circuit such as lamp brightness or motor speed?

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

Answer: (C)

To control how much current flows through a load like a lamp or a motor, you place a variable resistor in series and adjust its resistance. The device designed for this purpose is a rheostat. It’s a two-terminal variable resistor built to handle higher currents and the power those loads require. By turning the knob, you change the resistance, which limits the current and thus dims the lamp or slows the motor. Other options aren’t suited for this task. A preset variable resistor is small and intended for calibration with limited current. A potentiometer is a three-terminal device used as a voltage divider, not ideal for carrying large current. A capacitor isn’t a resistor at all and doesn’t set steady current in a DC path.

To control how much current flows through a load like a lamp or a motor, you place a variable resistor in series and adjust its resistance. The device designed for this purpose is a rheostat. It’s a two-terminal variable resistor built to handle higher currents and the power those loads require. By turning the knob, you change the resistance, which limits the current and thus dims the lamp or slows the motor.

Other options aren’t suited for this task. A preset variable resistor is small and intended for calibration with limited current. A potentiometer is a three-terminal device used as a voltage divider, not ideal for carrying large current. A capacitor isn’t a resistor at all and doesn’t set steady current in a DC path.