Tell me what you know about electricity

More than 2,500 years ago, the ancient Greeks discovered that amber rubbed with fur could attract small objects such as fluff and straw. They called this phenomenon "electricity."

In 1600 AD, the British doctor Gilbert (1544-1603) conducted many years of experiments and discovered many phenomena such as "electricity" and "electric attraction", and was the first to use "electricity", "Electric attraction" and other special terms, so many people call him the father of electrical research. In the 200 years after Gilbert, many people conducted many experiments and continued to accumulate understanding of the phenomenon of electricity. In 1734, the Frenchman Duval discovered the phenomenon that electricity of the same sign repels each other and electricity of different signs attracts each other. In 1745, Kleist, an archdeacon in Prussia (the predecessor of Germany), discovered the phenomenon of electrical discharge in experiments.

In the mid-18th century, on the other side of the ocean in the United States, the great electrician Franklin conducted many experiments, further revealing the nature of electricity and proposing the term current. He believed that electricity was a weightless fluid that existed in all objects. If an object receives more than its normal amount of electricity, it is said to be positively charged (or "positively charged"); if an object receives less than its normal amount of electricity, it is said to be negatively charged. (or "yin electricity"). The so-called discharge is the process of positive current turning into negative electricity. Franklin's statement was indeed able to explain some electrical phenomena quite satisfactorily at the time, but the understanding of the nature of electricity is inconsistent with our current view that "when two objects rub against each other, it is the negatively charged electrons that tend to move." It's the opposite.

Another major contribution of Franklin to electricity was through the famous kite experiment in 1752, "capturing lightning from the sky", proving that lightning in the sky and electricity on the ground are the same thing. He used metal wire to fly a large kite into the clouds. A piece of rope is connected to the lower end of the metal wire, and a bunch of keys are hung on the metal wire. At that time, Franklin held the rope with one hand and gently touched the key with the other hand. Immediately he felt a violent shock (an electric shock) and saw a small spark between his finger and the key. This experiment showed that the metal wire of the kite soaked by rain became a conductor, guiding the charge of the lightning in the air to between the finger and the key. This was a sensational event at the time. A year later Franklin created the world's first lightning rod.

The study of current phenomena is of great significance to people's in-depth study of electrical and electromagnetic phenomena. The first person to begin research on electric current was the Italian anatomy professor Galvani (1737-1798). Galvani's discovery originated from an extremely common lightning phenomenon in 1780. Lightning caused a frog's legs to convulse in contact with pliers and tweezers on the table in Galvani's dissecting room. His rigorous scientific attitude prevented him from giving up research on this "accidental" strange phenomenon. He spent 12 years studying the electrical effects of muscle movements like frog legs. Finally, he discovered that if nerves and muscles were brought into contact with two different metals, such as copper wire and iron wire, the frog's legs would spasm. This phenomenon occurs in a current loop. However, Galvani still could not answer the cause of this electric current phenomenon. He believed that the spasm of the frog's legs was a manifestation of "animal electricity" and that the circuit composed of metal wires was just a discharge circuit.

Galvani’s views aroused great repercussions in the scientific community at that time. However, another Italian scientist Volta (1745 ~ 1827) disagreed with Galvani’s views. He believed that electricity existed In metal, rather than in muscle, two apparently different opinions sparked debate in the scientific community and divided the scientific community into two major factions.

In the spring of 1800, there was a further breakthrough in the debate about the cause of the electric current. Volta invented the famous "voltaic battery". This battery is a device consisting of a series of circular zinc and silver plates overlapping each other. Between each pair of silver and zinc plates, there is a cardboard soaked in salt water or other conductive solution. . Silver flakes and zinc flakes are two different metals, and salt water or other conductive solutions serve as electrolytes, which form a current loop. This is a relatively primitive battery, a battery pack made up of many silver-zinc batteries connected together. But at that time, it was not easy for Volta to invent such a battery.

The invention of the voltaic battery enabled people to obtain a continuous current that could be artificially controlled for the first time, providing a material basis for future research on current phenomena, and also opened up prospects for the application of current effects, and soon Become a powerful tool for electromagnetic and chemical research.