{{fa>pencil?32}} You want to drive a red light-emitting diode with a voltage source of $U_{\rm s} = 5.0 ~\rm V$ and a current of $I_{\rm D} = 20 ~\rm mA$. You have found for red LEDs a voltage drop of $U_{\rm D} = 2.3 ~\rm V$ based on a web search. Now you want to know which resistor value from the E12 series (available to you) is correct as a shunt resistor. - Draw the circuit of the LED with a series resistor and plot the voltages. - What is the value of the series resistor $R_\rm V$ to get the given voltage drop $U_\rm S$? - Find the relationship between forward voltage and forward current in the datasheet of the red LED {{elektronische_schaltungstechnik:tlur640.pdf|TLUR6400}}. What voltage drop $U_\rm D$ can be determined from this datasheet for $I_{\rm D} = 20 ~\rm mA$ and what is the correct series resistance? \\ \\ - Briefly compare the different results considering the [[https://en.wikipedia.org/wiki/E_series_of_preferred_numbers#Lists|E12 series]]. \\ \\