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1. Read the text and find in it the answers to the questions that follow it.

An electric cell supplies electric energy provided its electrodes are of different materials. In case the electrodes are of the same material they become charged but there is no difference of potential across the terminals. Iron and zinc plates are commonly used for producing nega­tive electrodes since these materials produce a high charge. Carbon is commonly used to produce positive electrodes.

The voltage output of cells in use nowadays is from 1 to 2 V. The value of the output depends only on the materials used for the elec­trodes. Besides, it depends on the electrolyte of a cell. It does not de­pend on the size of a cell and its construction, while the current capac­ity of a cell depends on the size of the electrodes. The larger the size of the electrodes, the more current capacity they can supply. When the

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size of the electrodes is increased the current capacity also increases while the voltage output does not increase. Such is the relation between the size of the electrodes and the current capacity.

What element is described in the text?

In what case does a cell supply energy?

What materials are commonly used for producing negative electrodes?

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