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# The battery and electromagnetism

The key technologies in our story. Created by Brit Cruise.

## Want to join the conversation?

• Why exactly do bubbles form on the outside of the zinc and copper wires? I understand why the flow of electrons happens, but how does this translate to bubbles?
(95 votes)
• The process is called electrolysis, and it is a chemical reaction caused by a current. The bubbles are free ions, molecules with a negative charge.

Here is the Wikipedia snippet:

The main components required to achieve electrolysis are :
An electrolyte : a substance containing free ions which are the carriers of electric current in the electrolyte. If the ions are not mobile, as in a solid salt then electrolysis cannot occur.
A direct current (DC) supply : provides the energy necessary to create or discharge the ions in the electrolyte. Electric current is carried by electrons in the external circuit.
Two electrodes : an electrical conductor which provides the physical interface between the electrical circuit providing the energy and the electrolyte
(61 votes)
• if you just put pennies together would it make a battery? because it has copper and zinc
(20 votes)
• Yes! The only thing missing is an electrolyte (such as tap water, vinegar or even saliva!).
Here is a simple example I like to prove this to yourself.
- Find a (sanitized) piece of copper and zinc around the house:
- Touch them both to your tongue, but keep the metals separate.
- You will feel/taste nothing (except cold metal)
- Now while keeping the metals against your tongue, bring them together to they touch (so you have 3 points of contact, between the coins and on your tongue)
- Immediately you should taste an electric/acidic taste
- Separate the metals so they are not touching, the taste will stop!
(64 votes)
• Would this work with today's pennies? He's referring to copper, but I thought that past a certain year they stopped using so much copper. Nowadays, there's less copper in a penny than there used to be.
(17 votes)
• That's an interesting thought. Now days pennies are made out of zinc and then coated with copper. I'm guessing it would still work since the copper on the surface on the penny would still react with the solution but I'm not 100% on that.
(10 votes)
• At what happens if you dissconect the two metals. will the bubbles on the copper pop?
(13 votes)
• Yes they will stop (good question).
(13 votes)
• Is this similar to the process by which water is turned into it's constituent components (i.e. O2, & H) for making rocket fuel? thanks T.S.
(6 votes)
• Yes, water can be broken to its constituents oxygen and hydrogen by using electrolysis.
(3 votes)
• Do motors have something to do with an electromagnet?
(3 votes)
• So, they basically use copper and zinc in batteries? Then why are some batteries more expensive than others? :)
(3 votes)
• Not all batteries use copper an zinc. Some (like the kind in laptops, phones, and other power-hungry devices) use lithium-ion and lithium-polymer metals. Pretty much any two metals and one acid can and have been used as batteries, although alkaline (zinc'n'manganese dioxide), LiPo (lithum-ion+polymer) and LIon (lithium metal and lithum ion) are the most common.
(6 votes)
• Why does getting electrocuted result in muscle spasms during the electrocution? Why is electrocution represented by an X-Ray looking skeletons in cartoons?
(3 votes)
• I have no idea about the X-ray, but muscle spasms could be caused by your nerves. Your ,muscles, in computer terms, are analog activated flexion actuators.
In English, this means that your muscles can be activated by electric current and the degree of flex and movement can be controlled by the amount of current.
(4 votes)
• If I put something (like a phone charger) in the water (that's being charged by the battery), would it conduct electricity through the wire and charge my phone? Or would it not do anything?
(2 votes)
• If you put a phone charger in the water it will short out and possibly electrocute you. Don't put electronics in the water.
(3 votes)
• at what type of gas is the bubble?
(2 votes)
• I'm guessing oxygen, since the process is known as oxidization.
(2 votes)

## Video transcript

Consider the following experiment You have two pieces of metal: copper and zinc which you connect to conducting wires and you then submerge the metals in an electrolyte in this case vinegar You will observe that bubbles will form around the zinc but not on the copper. The metal seemed dissimilar in this way and if you then connect the two wires holding the metals, something changes. Tiny bubbles begin to form around the copper terminal. It seems as though something is being pulled from the zinc through the wire allowing a reaction to occur on the copper side and it turns out this is a flow of electrical charge as electrons are pulled away from the zinc towards the copper through the conductive path in the wire. Think of this blow as the result of a charge imbalance or electrical pressure between the two metals as compared to the instantaneous discharge observed with static electricity experiments. Towards the end of the 18th century Alessandro Volta had been investigating this effect. More importantly he found that chaining these cells together would amplify this flow of charge. And by 1800 he simplified things even further removing the jar which provided more electrolyte than was actually needed. He writes, "- A few dozen small round disks of copper, [pieces of coin for example], and equal number of plates of zinc. - I prepare circular pieces of spongy matter capable of retaining water - I continue coupling a plate of copper with one zinc and always in the same order and interpose between each of these couples a moistened disk. This continues until I have a column as high as possible without danger of it falling." This is known famously as the voltaic pile, the first battery in history to provide a continuous flow of electrical charge, or current. More cells resulted in an increased electrical pressure at the two ends and electrical pressure was an early term for what we now call voltage after Volta. Now if the two leads of a voltaic pile were brought into direct contact, a series of shocks could be observed. Now at first the utility of electric current as a communication method was not immediately obvious, aside from faint sparks and bubbles. One idea was to use the presence of bubbles to signal letters and the Bubble Telegraph used this method though it involved 26 different circuits, one for each letter and it was based on the fact that the battery providing the current can be placed at a distance away from the jars containing the leads creating the bubbles. An inventive although clumsy system which was never adopted. But very soon everything changed after a famous demonstration in 1819. It was found that if we simply pass a wire near a compass and connected to a battery as soon as the wire made contact with the battery the needle jumped without any physical contact. The only explanation was that the current carrying wire was creating a temporary magnetic field. This was followed by a series of tasks to figure out the direction of this field first we assumed it was pointing along the wire with the current or perhaps emanating outwards from the wire as heat would travel. But eventually it was deduced that it must be traveling around the wire in perpendicular circles, so a loop of wire would create a magnetic field which points through the center of the loop and around the outside. This lead to the galvanometer which was designed to detect and measure electrical current and it was just simply a coil of wire with a compass suspended in the center. Now when electric current was applied to the coil, a magnetic field would push through the middle of the coil and around the outside so the needle would always point perpendicular to the direction of the force which was balanced on either side of the needle, and the stronger the current the stronger the deflection of the needle. And by 1824 William Sturgeon demonstrated a way to increase the strength of this field even more, simply by wrapping a coil of wire around a piece of iron such as a nail the magnetic force could be amplified because iron seemed to be a better medium for supporting the formation of magnetic fields. We call this "permeability" and by wrapping the wire many times the strength of the field could be amplified thousands of times and this is known as an "electromagnet". So suddenly it was possible to create magnetic fields which could move needles with precision and force using electric current applied at a distance using a long loop of wire and a strong battery. At the time our understanding of information was in its infancy. People were thinking about information and a message as the number of letters in a message so the goal was intuitive: who could come up with the fastest way to transmit letters and whoever had the fastest system would therefore reduce the cost per message for the sender using this system. And a gold mine was waiting for whoever got there first.