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Solved exercise · level 3 of 5

Under-supplied lamp

Skills: Analyse

Statement

Lamp L1 is rated 10 W - 6 V, but it is supplied at only 3 V (half).

What power does it really dissipate? (Assume its resistance constant.)

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

3 hints from Bastaya available in the lab
Solution

R = 6² / 10; at 3 V, P = 3² / R = 2.5 W, a quarter of the rated power: the lamp glows dimly.

Course sheet of the chapter : Power, energy, efficiency

This chapter is covered by the paths: General electricity

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

Del
delete
R
rotate
C
chip brush
Esc
cancel
wheel
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fit the board
drag background
pan

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