Replace the question mark with a number
MATH PUZZLE: Can you replace the question mark with a number?Correct answers: 490
The first user who solved this task is Vladimir Krnac.
#brainteasers #math #riddles
Edison patentIn 1922, Thomas A. Edison was issued a U.S. patent for a "Storage-Battery Electrode and the Production of Same" (No. 1402751). The electrodes were intended for batteries of the Edison type using nickel hydroxide for the active material for the positive elements and electrolytically active iron as the active material for the negative elements in an alkaline solution. The improved electrode element was designed to provide a high discharge rate by decreasing the internal resistance of the cell. The electrode element consisted of a thin metallic plate with small and closely adjacent perforations. The metal surface had a thin coating or film of a hydroxideof a suitable metal (preferable nickel) applied by electrolytic deposition.«[Image: one of the patent diagrams showing a fragmental sectional view of the electrode element.] |