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Solved exercise · level 3 of 5

Two accumulators in opposition

Skills: Calculate

Statement

A circuit contains two accumulator cells (e = 1.2 V, r = 0.02 Ω and e′ = 2 V, r′ = 0.01 Ω) connected in opposition through a resistance R = 0.02 Ω. What is the current when the circuit is closed?

e = 1.2 V · r = 0.02 Ω · e′ = 2 V · r′ = 0.01 Ω · R = 0.02 Ω

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

The stronger one (e′) sets the direction: ΣE − ΣE′ = ΣR · I → I = (e′ − e) / (r + r′ + R) = (2 − 1.2) / (0.02 + 0.01 + 0.02) = 16 A. Cell e is being recharged.

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.

Shortcuts

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C
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