13 10-cent coins, 13 one-cent coins, and 13 pins, plus a cup of salt water can do?
The answer: the ability to make a 1.5 volt battery!
Pour the salt in various small grid about 3 / 4 full (as maps, can be directly used in the common refrigerator ice boxes) will be two kinds of coins in a previous post with a pin connection is good, and then follow the diagram look like a month organizations line up (note the order of copper and silver). Finally put a small LED lights will really light Oh!
Note: The figure above mentioned fact, before the year 2001 should be before 1983 because before 1983 almost all of the Pennies are copper or bronze, so very good electrical conductivity, while the policy change after 1983 all of the Pennies are galvanized, electrical conductivity on the poor. But I think that here, instead of using the words of effect of copper should be the same.
like the wild friend, can not be made reference to prepare for rainy day!