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T2 CH2 Electricity — Science STD 7 — Question

Tamilnadu BoardEnglish MediumSTD 7ScienceT2 CH2 Electricity5 Marks
Question
Explain the construction and working of a dry cell.
✓

Answer

  1. A dry cell is a portable form of a leclanche cell.
  2. It consists of zinc vessel which acts as a negative electrode or anode.
  3. The vessel contains a moist paste of saw dust saturated with a solution of ammonium chloride an chloride.
  4. The ammonium chloride acts as an electrolyte.
  5. The purpose of zinc pide is to maintain the moistness of the paste being highly gyroscopic.
  6. The carbon rod covered with a brass cap is placed in the middle of the vessel. It acts as positive electrode or cathode.
  7. It is surrounded by a closely packed mixture of charcoal and manganese dioxide ($Mn0 _2$) in a muslin bag.
  8. Here $Mn0 _2$ acts as depolarizer. The zinc vessel is sealed at the top with pitch or shellac.
  9. A small hole is provided in it to allow the gases formed by the chemical action to escape.
  10. The chemical action inside the cell is the same as in avalanche cell.

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