Gold

Gold has captivated civilizations since we have been tracking the history of the world.   The shiny, dense and malleable characteristics make it very suitable for many applications.

Gold was used in ancient times to build idols, vases and jewelry, among other things.  Later it became a form of trade; people traded goods for gold, it was at this point in time (about 700 B.C.), when gold was given a "monetary value".  Gold became the metal used to make coins; The Roman and Greek empires utilized gold to obtain (buy) goods from other parts of the world.

Today gold is not longer used to make money, however, coins are made in different countries that are used for investment purposes.  Investors buy gold in the form of coins or bars.  Coins come in weights of up to 1 oz of pure gold, while bars come in weights of up to 100 oz.

Gold is also used as an ingredient in food.  Poland and Germany produce a drink called goldwasser that contains very tiny flakes of gold, which are used to give the drink a particular sparkling look.  Gold ingested in very small quantities does not cause any issues to the body.

Gold made products can contain different amounts of gold.  This amount of gold is defined as the number of carats.  Pure gold is designated as 24k (k = carat).  In jewelry you normally find gold in 18k (75% gold) and 14k (~58% gold).  24k gold is rarely used in jewelry, as pure gold wears out very easily with friction.  The most common metal used as alloy is copper; 18k gold contains 75% gold and 25% copper, although, other metals are also used such as silver, bronze, palladium and nickel.

How does Electricity Work?

Electricity can be at rest (static electricity) or in motion (dynamic electricity).  Static electricity is the presence of an electric charge, either positive or negative.  All of us have experienced shocks, caused by static electricity in our clothes and body, when we have made contact with an object with an opposite charge.  The shock felt is caused by the charge moving from a resting position to a dynamic position, flowing from the negatively charged object to the positively charged.

The flow of electricity is caused by a potential difference; when the two charged objects make contact, electrons will move from the object with the highest charge to the one with the lowest.  This can be compared to water flowing inside a pipe from a second story to the basement of a house; the force of gravity makes the water go down (the difference in height is the potential difference).

When electrons move from one place to another due to the potential difference (voltage), they do it to stabilize the charge between the two objects.  Think about a river flowing into a lake, if the lake is empty, water will drop from the river’s mouth into the lake and start filling it up.  When the lake fills up and the water reaches the mouth of the river, the water will stop dropping because the water in the lake is at the same level (potential) that the water at the river.

Electronic equipment in our homes, car, offices and everywhere else, work by the applied use of dynamic electricity.  When such equipment is turned off, the electricity is at rest because there is no potential difference; no voltage is being applied.

When we turn the equipment on, a battery or the power outlet from the wall, provides a potential difference which causes electrons to start moving inside the circuits.  These circuits are designed by electrical engineers such that the flow of electrons will achieve a particular function.  These functions can be:

To control microscopic switches (transistors) in order to exchange information; such as in computers.

To create electro-magnetic fields used to send signals into the air; such as in radio transmitters or to display images on a television display.  And many other applications.

Using our previous analogy of water pipes in a house, the water can also travel from the basement to the second story because of the pressure created by a water pump.  This water pump has the same purpose as a battery; to provide a potential difference in order to start the flow of water (caused by the applied pressure), or to start the movement of electrons, in the case of the electronic circuit with the battery (caused by the chemical energy stored in the battery).

Our next issue will talk about how batteries work and how they store “chemical energy” which is then transformed into “electrical energy”.