Hallo!

Der MisterMou hat es ausgerechnet und ich habe es inzwischen skizziert:
Code:
           I               I-0,5A
         ----->            ----->
       +--------+        +--------+-----
       |        |        |        |    A
       |        |        |       .-.   |
       |        |        |       | |Rv | 20V
       |        |        |       | |   |
       |        |        |       '-'   |
      /+\       |       /+\       |    V
     ( U )      |      ( U )      +-----
      \-/       |       \-/       |    A
       |       .-.       |       .-.   |
       |       | | Rs    |       | |Rs | U-20V
       |       | |       |       | |   |
       |       '-'       |       '-'   |
       |        |        |        |    V
       +--------+        +--------+-----

       U = I * Rs        U - 20 V
                         -------- = I - 0,5 A
                            Rs

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