Clark cell

Clark - standard, a special element is galvanic cell, which provides a stable DC voltage. She served in the early days of electrical engineering as a reference voltage source, and was invented in 1874 by the British engineer Josiah Latimer Clark.

Construction

In Clark standard cell, the anode consists of an amalgam of zinc and mercury, the so-called zinc amalgam, in the figure on the right side and with the terminal K1 connected. At the bottom of the cell, the cathode of liquid mercury, which is connected through the electrolyte with an insulating glass rod to terminal K2. The electrolyte consists of an aqueous zinc sulfate solution and saturated. As a depolarizer is mercury (I ) sulfate ( Hg2SO4 ).

The Clark - normal element has at a temperature of 15 ° C an open circuit voltage of 1.4328 V. The removable electrical current must be as low as possible.

Clark normal element has some drawbacks such as a relatively high temperature coefficient of -1.15 mV / ° C, and corrosion problems in the region of the connection wires to the zinc amalgam. The Clark - normal element was replaced in the wake of the more temperature- Weston- normal element.