Resistor Types Explained: From Potentiometers to Thermistors

Resistors come in a variety of shapes and functions, each tailored to specific electronic needs. Understanding the key differences between these common types—potentiometers, rheostats, thermistors, and photoresistors—helps engineers choose the right component for any circuit.

Potentiometers are three‑terminal variable resistors that serve as adjustable voltage dividers. They are ideal for low‑current applications such as volume controls or sensor calibration. Rheostats, in contrast, are typically two‑ or three‑terminal devices designed to handle higher currents; they are often used as variable fuses or motor speed controls.

Thermistors are temperature‑dependent resistors that change resistance sharply with ambient temperature. Negative temperature coefficient (NTC) thermistors decrease in resistance as temperature rises, while positive temperature coefficient (PTC) thermistors increase in resistance, making them useful for temperature sensing, over‑current protection, and self‑regulating heating elements.

Photoresistors—or light‑dependent resistors (LDRs)—adjust resistance based on incident light intensity. They are widely employed in light‑sensing circuits, such as automatic street lights, night‑lights, and camera exposure controls.

RELATED WORKSHEETS:

• Potentiometers Worksheet
• Resistors Worksheet