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Solved exercise · level 3 of 5

Limiting the charging current

Skills: Calculate

Statement

A lead cell (e = 2.2 V, r = 0.01 Ω) and a nickel-iron cell (e′ = 1.2 V, r′ = 0.05 Ω) are connected in opposition. What resistance must be added so that the current does not exceed 2 A when the circuit is closed?

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

2 hints from Bastaya available in the lab
Solution

e − e′ = (r + r′ + R) · I → R = (e − e′) / I − r − r′ = (2.2 − 1.2) / 2 − 0.01 − 0.05 = 0.44 Ω.

Course sheet of the chapter : Real generators & loads

This chapter is covered by the paths: General electricity, Measurement prep, 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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