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| lab_electrical_engineering:1_resistors:nonlinear-resistors [2026/03/10 03:40] – mexleadmin | lab_electrical_engineering:1_resistors:nonlinear-resistors [2026/03/16 01:59] (current) – mexleadmin |
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| ==== Nonlinear resistors ==== | ====== Non-linear resistors ====== |
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| 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>. | All resistors examined so far are linear resistors, for which the characteristic $I = f(U)$ is a straight line; see <imgref Fig-6_Linear-resistors_V1>. The resistance of a linear resistor is independent of the current $I$ flowing through it and of the applied voltage $U$. |
| The resistance value of a linear resistor is independent of the current $I$ flowing through it or the applied voltage $U$. | |
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| {{drawio>lab_electrical_engineering:1_resistors:Fig-6_Linear-resistors_V1.svg}}\\ | {{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> | <imgcaption Fig-6_Linear-resistors_V1 | Characteristic of a linear resistor> </imgcaption> |
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| 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: | |
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| $$ R = \frac{U}{I} $$ | For non-linear resistors, there is no proportionality between current and voltage. The characteristic of such a resistor is shown in <imgref Fig-7_Nonlinear-resistors_V1>. For these resistors, one distinguishes between static resistance $R$ and dynamic (or differential) resistance $r$. |
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| The differential resistance around the operating point is calculated from the current difference caused by a change in the applied voltage: | The static resistance is determined for a specific operating point: at a given voltage, the current is read from the characteristic. The calculation is carried out according to Ohm's law: |
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| $$ r = \frac{\Delta U}{\Delta I} $$ | $R = \frac{U}{I}$ |
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| | The dynamic resistance around the operating point is calculated from the current difference caused by a change in the applied voltage: |
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| | $r = \frac{\Delta U}{\Delta I}$ |
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| {{drawio>lab_electrical_engineering:1_resistors:Fig-7_Nonlinear-resistors_V1.svg}}\\ | {{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> | <imgcaption Fig-7_Nonlinear-resistors_V1 | Characteristic of a non-linear resistor> </imgcaption> |
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| 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>. \\ | An incandescent lamp is investigated as an example of a non-linear resistor. Build the measurement circuit shown in <imgref Fig-8_light-bulb_V1>. \\ |
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| {{drawio>lab_electrical_engineering:1_resistors:Fig-8_light-bulb_V1.svg}}\\ | {{drawio>lab_electrical_engineering:1_resistors:Fig-8_light-bulb_V1.svg}}\\ |
| <imgcaption Fig-8_light-bulb_V1 | Measuring circuit light bulb> </imgcaption> | <imgcaption Fig-8_light-bulb_V1 | Measurement circuit for incandescent lamp> </imgcaption> |
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| 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>. | 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>. |
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| {{drawio>lab_electrical_engineering:1_resistors:Table-6_light-bulb_V1.svg}}\\ | {{drawio>lab_electrical_engineering:1_resistors:Table-6_light-bulb_V1.svg}}\\ |
| <tabcaption Table-6_light-bulb_V1 | Values characteristic curve light bulb> </tabcaption> | <tabcaption Table-6_light-bulb_V1 | Measured values for the incandescent-lamp characteristic> </tabcaption> |
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| Create the characteristic curve $I = f(U)$, s. <imgref Fig-9_light-bulb-curve_V1> | Plot the characteristic $I = f(U)$. |
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| | Calculate the static resistance $R$ at the operating point $U = 7.0 ~{\rm V}$. |
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| {{drawio>lab_electrical_engineering:1_resistors:Fig-9_light-bulb-curve_V1.svg}}\\ | Calculate the dynamic resistance $r$ at the operating point $U = 7.0 ~{\rm V}$. |
| <imgcaption Fig-9_light-bulb-curve_V1 | Characteristic curve light bulb> </imgcaption> | \\ \\ \\ \\ |
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| Calculate the static resistance $R$ at the operating point $U = \rm 7.0 ~V$: | |
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| Calculate the dynamic resistance $r$ at the operating point $U = \rm 7.0 ~V$: | |
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| Compare the values with the values from <tabref Table-1_V2> (direct resistance measurement) | |
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| | Compare the values with those from the direct resistance measurement (<tabref Table-1_V2>). |
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