Elec Class

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Solved exercise · level 3 of 5

Resistivity of a metal

Skills: Calculate

Statement

What is the resistivity of the metal of a wire with resistance 11.2 Ω, length 2 m and diameter 0.5 mm? (Answer in Ω·mm²/m.)

R = 11.2 Ω · l = 2 m · D = 0.5 mm

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

Guided problem in 4 steps: unknown, formula, units, data, result.

1 hint from Bastaya available in the lab
Solution

S = π·D²/4 = 0.196 mm²; ρ = R·S/l = 11.2 × 0.196 / 2 ≈ 1.1 Ω·mm²/m: it is nichrome.

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.

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