characteristics line
A characteristic curve is a graphical representation that shows the dependence of two quantities in a two-dimensional coordinate system. The two quantities can be physical quantities such as current, voltage, resistance, temperature or other quantities that are directly related to each other.
The coordinate system must be able to represent the relationship between the two physical quantities. The type of coordinate system and the division of the axes, whether linear or logarithmic, should be selected in such a way that an optimum characteristic curve representation is given, from which the user can read off the relationship between the two quantities. The characteristic curve itself is a line representing the dependence of one physical quantity on the other.
Every passive and active electronic component is characterized by its characteristic curve. Whether resistor or inductor, diode or transistor, battery or solar cell, every component has characteristic quantities that are related to other quantities: Current to voltage, temperature to resistance, voltage to time, etc. A very often used characteristic is the I-V curve, which shows the dependence of the current on the voltage. For a resistive resistor, this dependence is linear: as the voltage increases, the current increases linearly. For other components such as diodes, the dependence is non-linear.
If you look at a resistance characteristic curve of an ohmic resistor, there is a linear relationship between voltage and current. However, this will change as a function of another physical quantity such as temperature. For a lower temperature, there is a different characteristic curve than for a higher temperature. If several characteristic curves contribute to the representation of a third physical quantity, this is called a characteristic curve field.