Why we should used Non linear Resistor?

Why we should used Non linear Resistor? Non Linear Resistor: The behavior of a substance (usually a semiconductor) which does not obey Ohm's law but has a voltage drop across it that is proportional to some power of the current. Its value will not constant. We used Non linear resistor because its value is not constant. When a circuit require resistor to change value with a change in temperature or light then to be Non linear resistor. As its value not constant so we can define different value for use the circuit. Some characteristics of Non linear resistor: # Positive Temperature Co-efficient (PTC): When temperature rise then resistance increase. Like PTC resistor (BaTi03). PTC thermistors are used for voltage and/or current overload protection, temperature Protection, inrush current generation, and as a heating element. # Negative Temperature Co-efficient (NTC): when temperature rises then resistance lowers. Like NTC resistor (Ni, Mn). NTC thermistors are used for over temperature protection in PCs, power supplies, and motherboards; Li-ion battery protection in fast chargers; and in digital scan cameras, fire and smoke Detectors, TCXOs, and other automotive, consumer, and industrial applications. # Voltage Dependable (varistors): When voltage exceeds a certain value then resistance critically lowers. Varistors are used for transient surge suppression. Surge suppression circuits are commonly used in computers, automobiles, telecom and industrial equipment, domestic appliances, and other consumer products. # Light Dependable (LDR): when increase light then resistance lowers. For example, solar powered garden lights, and night security lighting. Above characteristics made Non linear resistor to use the circuit Comfortable. Because if we used that types characteristics resistor in a circuit then we get overload protection, different voltage range, large resistance, large temperature, switch on delay, chip thermistor, over voltage protection, customized types available upon request, several execution(naked,tape,SMD,lead frame) .It can used to like a logical switching circuit.