Rheostat vs Potentiometer-difference between Rheostat and Potentiometer

This page compares Rheostat vs Potentiometer and mentions difference between Rheostat and Potentiometer.

Rheostats and potentiometers are devices which vary resistances in order to change amount of current or voltage in the circuit.

Rheostat

• The device Rheostat has two terminals.
• They can be connected in series with the load and voltage source.
• The figure depicts rheostat.
• As shown it varies the current.
• Resistance increases when wiper is moved up and decreases on the other side.
• The Rheostat must have wattage rating high enough for maximum I when R is minimum.

Potentiometer

• It has three terminals.
• The ends of potentiometer are connected across the voltage source.
• The third variable arm as shown is used to tap the part of the voltage.
• The applied voltage V is input to the two end terminals of the potentiometer.
• The variable V is output between variable arm and end terminal.
• The potentiometer may be used as rheostat by simply using wiper terminal and one of the other terminals. The third terminal is left unconnected and unused.