A resistor is a passive electrical component that provides resistance to the flow of electric current in a circuit. In the context of sensors, resistors are often used to help in the measurement, detection, or calibration of physical quantities by converting them into a measurable electrical signal. For example, in a temperature sensor (thermistor), the resistance of the sensor changes with temperature; by measuring this change in resistance, the temperature can be determined. Similarly, in a light-dependent resistor (LDR), the resistance changes with variations in light intensity, allowing for light measurement. Thus, resistors in sensors are key to translating various physical parameters into electrical signals that can be easily measured and processed.