CBSE Class 10 Answered

Construction

• It consists of a zinc container with a small brass cap on one side of the cell which is labelled as positive (+) and a metal base at the other side of the cell which is labeled as negative (-).
• The positive and negative sides of the cells are called as positive terminal and negative terminal of the cell respectively.
• A carbon rod is placed at the centre of the cell surrounded by a mixture of manganese dioxide (MnO₂) and charcoal (C) in a muslin bag.
• The electrolyte is a moist paste of ammonium chloride (NH₄CI), plaster of paris, flour, etc. and the outer body (except for the base) of a zinc container is insulated with a thick cardboard or plastic material.

Working

• When the cell is connected to a bulb, the chemical reaction inside the cell becomes fast and the current starts flowing through the bulb. Hence, the bulb glows.
• These dry cells are a small source of electricity.

Note:The dry cells actually are not dry. In fact, it works as long as the paste inside it remains moist. The presence of water (or moisture) helps in the movement of the ions within the cell from one electrode to the other.