Category: Magnetism and Electricity

This section take you through the discoveries in magnetism and electicity through time, in the order they where discovered. With experiments you can do at home to replicate the discoveries.

1745 – Capacitor/Layden Jar

1745 – Capacitor/Layden Jar – Pieter van Musschenbroek

Pieter van Musschenbroek and his assistant, while trying to get sparks using glass with in it water, a wire and a charged  glass tube.  His assistant held the jar in his left and with the wire in the water and the other end of the wire in the charged tube.
When he touch the wire there was a large spark and he felt a in his body.

Later they would add a stopper and wire with a ball.  This became know as the layden jar, named after the  university of Leyden where the experiment was done.

There was another person Von Kleist who may have done the experiment first, but Pieter van Musschenbroek account was clear and repeated by other. 

Pieter van Musschenbroek was also the first to use the term physics.

Experiment – Layden Jar

1729 – Conduction

1729 – Conduction – Stephen Gray

Stephen Grey was a dyer by profession, but had interests in astronomy and natural sciences. His education  was mostly self educated.  We he retiremented he experimented with static electricity. In one experiment he used a glass tube which he kept the ends closed with cork, to keep the tube clean.

He noticed that when he rubbed the glass tube the cork, attracted items. He put a stick into the cork and was able to extend attraction. He began to do experiments to see how far he could extend the effects.

This was the beginning of experiments with conduction, the ability to move electrons through materials.

Experiment – Conduction

1709 – Glowing discovery

Hauksbee

1709 – Glowing discovery – Francis Hauksbee Francis Hauksbee, also known as Francis Hauksbee the elder, experimented with mercury after hearding of the account that the french astronomer Jean Picard in 1675 had observered a faint glow while caring a mecury barometer.

He discovered that mercery in a glass cantainer exposed to static electricitity can glow bright enough to read by.   This is called electroluminescence.

Francis Hauksbee make a modified static electric generator like Otto von Guericke’s, which had mercury in the glass ball with a partial vacuum.  When it was spun and a hand placed on it, it gave off light.

Experiment – Glowing discovery

1660 – Static electric generator

1660 – Static electric generator – Otto von Guericke

Otto von Guericke invented the first static electric generator. It was a sulfur ball on a rod that can be hand cranked and rubbed with a object to generate static electricity. He heard crackling and felt the hairs sand on end. Soon other in Europe were copying it and making improvements.

Experiment – Static Electric generator

1629 – Repulsion of like charges

1629 – Repulsion of like charges – Niccolò Cabeo

Niccolò Cabeo May have been the first to notice that object with the same charged are repelled from each other.  He wrote a book on magnetic philosophy (“Philosophia magnetica”).  Where he descibe metal filing being attracted to a charged object, but once they touched the charged object they are repelled by it.

Experiment – Repulsion

1600 – Versorium Electroscope

1600 – Versorium Electroscope – William Gilbert

In 1600 William Gilbert, the queen physician, published a book called De Magnete (Latin for “On the Magnet”) . It became the standard for magnetism and electricity. He developed a tool to detect electric charges (electroscope), which he called a versorium. It consisted of a needle on a pivot. He was also to use the term, in Latin, for electric force. He was also the first to realize that the earth was a giant magnet.

Experiment – Versorium

1742 – Electrostatic Bells

1742 – Electrostatic Bells – Andrew Gordon

About 1742 Andrew Gordon, a Professor of Natural Philosophy at the University at Erfurt in Germany, invented the Electrostatic Bells. It was the first invention to convert electrical energy into mechanical energy. Benjamin Franklin later used this invention to detect lighting storms and they became more commonly known as “Franklin Bells”.

Experiment – Electrostatic Bells

1748 – early electroscope

1748 – Jean-Antoine Nollet – Early electroscope

In 1748 Jean-Antoine Nollet built an early electroscope, an electrometer comprised of a suspended pith ball that moves in response to the electrostatic attraction and repulsion of a charged body.

It was a metal box with  isolated wire hung down and a piece of metal foil hanging down.  With a special lense  they amount of movement of the foil could be measured.

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Experiment – Early electroscope

1752 – charges

1752 – Charges – Benjamin Franklin

In 1752 Benjamin Franlin through a series of experiment realized that electricy was not 2 different things, but one thing with 2 different charges.  He called one plus and the other negitive.  How he identified them, assign the negitive charge to the side with excess eletrons.  That is how a electron beame to be known as having a negitive charge.

Experiment I – Forms of electricity

4 BC – The Compass – China

Chinese South Pointing Device

In the Chinese book “Book of the Devil Valley Master” (鬼谷子) is mentioned a “south pointing device” or compass. It was used at the time for fortune telling1.

Magnetized needle compass

The first reference to using a magnetized need a magnetized needle happens around around 1088, in the Dream Pool Essays by Shen Kuo. It isn’t until 1119 that the use of a magnetized needle compass was used for navigational purposes in Zhu Yu‘s book Pingzhou Table Talks (萍洲可談).

A magnetized needle compass was first mentioned in western literature written about 1180 by Alexander Neckam in De Utensilibus (On Instruments).

Experiment – make a compass