Certainly, I'd be happy to explain nonlinear resistors and their basic concepts in electricity.
A resistor is a fundamental component in electrical circuits that resists the flow of electric current. In linear resistors, the relationship between voltage across the resistor (V) and current passing through it (I) is linear and follows Ohm's law: V = I * R, where R is the resistance of the resistor.
Nonlinear resistors, on the other hand, do not follow Ohm's law and have a more complex relationship between voltage and current. The resistance of a nonlinear resistor changes with the applied voltage or current. This can lead to interesting and sometimes unpredictable behavior in circuits.
There are two common types of nonlinear resistors:
Varistors: A varistor, short for "variable resistor," is a nonlinear resistor with a voltage-dependent resistance. It is often used as a voltage-clamping device to protect electronic circuits from voltage surges. When the voltage across a varistor exceeds a certain threshold (known as its breakdown voltage), the resistance drops significantly, allowing it to conduct current and divert excess voltage away from the circuit.
Thermistors: A thermistor is a temperature-sensitive resistor. Its resistance changes with temperature. There are two main types of thermistors: positive temperature coefficient (PTC) and negative temperature coefficient (NTC) thermistors. PTC thermistors have increasing resistance as temperature rises, while NTC thermistors have decreasing resistance as temperature rises. Thermistors are used for temperature sensing, temperature compensation, and in applications where temperature control is important.
The behavior of nonlinear resistors can be described using various equations and models that relate resistance, voltage, current, and sometimes temperature. These models might be more complex than the simple linear relationship found in Ohm's law, and they often involve exponential or power-law equations.
Nonlinear resistors play important roles in circuit protection, temperature sensing, and various applications where controlled nonlinearity is desired. Understanding their characteristics is crucial for designing circuits that exhibit the desired behavior in different operating conditions.