DW EditShow pageOld revisionsBacklinksAdd to bookExport to PDFFold/unfold allBack to top This page is read only. You can view the source, but not change it. Ask your administrator if you think this is wrong. ==== Nonlinear resistors ==== \\ All resistors examined so far are linear resistors, for which the characteristic curve $I=f(U)$ is a straight line, s. <imgref Fig-6_Linear-resistors_V1>. The resistance value of a linear resistor is independent of the current $I$ flowing through it or the applied voltage $U$. {{drawio>lab_electrical_engineering:1_resistors:Fig-6_Linear-resistors_V1.svg}}\\ <imgcaption Fig-6_Linear-resistors_V1 | Characteristic curve of a linear resistor> </imgcaption> \\ With nonlinear resistors, there is no proportionality between current and voltage. The characteristic curve of such a resistor is shown in <imgref Fig-7_Nonlinear-resistors_V1>. With these resistors, we talk about static resistance ($R$) and dynamic (or differential) resistance ($r$). The static resistance is determined for a specific operating point: at a specific voltage, the current is read from the resistance characteristic curve. \\ The calculation is performed according to Ohm's law: $$ R = \frac{U}{I} $$ The differential resistance around the operating point is calculated from the current difference caused by a change in the applied voltage: $$ r = \frac{\Delta U}{\Delta I} $$ {{drawio>lab_electrical_engineering:1_resistors:Fig-7_Nonlinear-resistors_V1.svg}}\\ <imgcaption Fig-7_Nonlinear-resistors_V1 | Characteristic curve of a nonlinear resistor> </imgcaption> A light bulb is examined as an example of a nonlinear resistor. Set up the measuring circuit shown in <imgref Fig-8_light-bulb_V1>. \\ {{drawio>lab_electrical_engineering:1_resistors:Fig-8_light-bulb_V1.svg}}\\ <imgcaption Fig-8_light-bulb_V1 | Measuring circuit light bulb> </imgcaption> \\ Set the voltage on the power supply to the voltage values from <tabref Table-6_light-bulb_V1>. Measure the corresponding current values and enter them in <tabref Table-6_light-bulb_V1>. {{drawio>lab_electrical_engineering:1_resistors:Table-6_light-bulb_V1.svg}}\\ <tabcaption Table-6_light-bulb_V1 | Values characteristic curve light bulb> </tabcaption> \\ Create the characteristic curve $I = f(U)$, s. <imgref Fig-9_light-bulb-curve_V1> {{drawio>lab_electrical_engineering:1_resistors:Fig-9_light-bulb-curve_V1.svg}}\\ <imgcaption Fig-9_light-bulb-curve_V1 | Characteristic curve light bulb> </imgcaption> Calculate the static resistance $R$ at the operating point $U = \rm 7.0 ~V$: \\ \\ \\ \\ Calculate the dynamic resistance $r$ at the operating point $U = \rm 7.0 ~V$: \\ \\ \\ \\ Compare the values with the values from <tabref Table-1_V2> (direct resistance measurement) CKG Edit