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Solved exercise · level 2 of 5

Resistance of a wire with the ohmmeter

Skills: Calculate, Measure

Statement

Wire F1 is made of copper (ρ = 0.017 Ω·mm²/m), 100 m long, 2.5 mm in diameter. Ohmmeter O1 is connected across it but its display is hidden.

Compute the resistance the ohmmeter will show.

Parametric exercise: the values change with every draw; these are one example.

3 hints from Bastaya available in the lab
Solution

S = 4.91 mm²; R = ρ·l/S = 346 mΩ. The ohmmeter confirms: 346 mΩ (de-energised measurement).

Course sheet of the chapter : Ohm's law & resistance

This chapter is covered by the paths: ISL-oriented exercises

Other exercises of the chapter

Simulated time00:00:00
Q = I·t-
W = P·t-

Circuit diagram CEI 60617

How does it work?

Each big hole is a circuit node: you push one leg of a component into it. The 4 small holes around it are connected to it: chips and leads plug in there.

  1. Place a component Drag it from the palette: it snaps onto the grid. R rotates it.
  2. Bridge neighbouring holes Pick the jumper chip (or C) and drag on the board: bridged holes become a single node.
  3. Draw a lead For long links and the power supply: from one big hole to another, or to a terminal.
  4. Close the loop The circuit is solved live (Ohm, Kirchhoff) and the diagram follows.

Shortcuts

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C
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