Two or more cells make a battery
A torch takes two cells. Put one in the wrong way round, and the lamp stays dark.
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The idea
Step 1 of 3
- One cell, the ordinary way. The lamp lights.
- A second cell, the same way round. The lamp still lights.
- One cell is turned round. The cells push against each other. The lamp is dark.
Two or more cells joined together make a battery.
The rule
Each cell pushes current round the loop. Joined + to −, their pushes act the same way. Equal pushes in opposite ways cancel each other.
Join the + of one cell to the − of the next. Turn one of two cells round, and their pushes cancel. The lamp stays dark.
Nothing is broken when this happens. Every part still looks fine.
Watch out!
In everyday talk, a single cell is often called a battery too. In this chapter, a battery is two or more cells.