| 6 | | [[Image(SLA_battery.jpg,right,20%,nolink)]] |
| 7 | | Batteries have two electrical terminals and chemicals between them. The terminals and chemicals are chosen so that they can react chemically, for the reaction to work, one terminal needs to lose electrons and the other needs to gain them. So when electrons can move from one terminal to the other, the chemical reaction proceeds. Normally, the battery terminals are separated by air which resists the flow of electrons, but if the terminals are connected together with a wire or other material that allows electrons to flow, the reaction proceeds as long as electrons flow from one terminal to the other. |
| | 6 | [[Image(sla_battery.jpg,right,15%,nolink)]] |
| | 7 | Batteries have two electrical ''terminals'' and chemicals between them. The terminals and chemicals are chosen so that they can react chemically, for the reaction to work, one terminal needs to lose electrons and the other needs to gain them. So when electrons can move from one terminal to the other, the chemical reaction proceeds. Normally, the battery terminals are separated by air which resists the flow of electrons, but if the terminals are connected together with a wire or other material that allows electrons to flow, the reaction proceeds as long as electrons flow from one terminal to the other. |
| 9 | | * The battery terminal that supplies electrons is called the negative terminal and is usually marked with a black color or '-' sign. |
| 10 | | * The battery terminal that consumes electrons is called the positive terminal and is usually marked with a red color or '+' sign. |
| | 9 | * The battery terminal that supplies electrons is called the ''negative'' terminal and is usually marked with a black color or '-' sign. |
| | 10 | * The battery terminal that consumes electrons is called the ''positive'' terminal and is usually marked with a red color or '+' sign. |
| | 11 | |
| | 12 | Batteries can be made from a wide variety of chemical reactions. You can make a battery yourself using a [http://www.wikihow.com/Create-a-Potato-Battery potato] or a [https://www.scientificamerican.com/article/generate-electricity-with-a-lemon-battery/ lemon]. Common commercial batteries include carbon-zinc, alkaline, lithium, and lead-acid. Because they are chemical devices, batteries vary widely in size, capacity, and characteristics. In general, the larger the battery, the more chemicals it contains and the more electrical energy it can generate through the chemical reactions. |
| 13 | | The difference in electrical potential between the two terminals is measured in units of Volts (named after [https://en.wikipedia.org/wiki/Alessandro_Volta Alessandro Volta]). Voltage is *potential* energy, like the reservoir/lake behind a hydroelectric dam; no work is being done if the water isn't flowing, but you can measure the pressure the water is exerting on the dam. It's important to recognize that voltage is just a potential, no work is being done by voltage, it represents a difference in charge, the strength of attraction between two opposite charges. There are many different types of batteries that use different types of chemical reactions to generate that charge potential difference. The oldest type of battery, and the one we still use on our robots, is the [https://en.wikipedia.org/wiki/Lead%E2%80%93acid_battery lead-acid] battery which uses lead terminals and sulphuric acid. These batteries produce 2 volts per cell; if you put 6 of them together in sequence, you can get 12 volts. |
| | 15 | The difference in electrical potential between the two terminals is measured in units of Volts (named after [https://en.wikipedia.org/wiki/Alessandro_Volta Alessandro Volta]). Voltage is *potential* energy, like the reservoir/lake behind a hydroelectric dam; no work is being done if the water isn't flowing, but you can measure the pressure the water is exerting on the dam. Voltage is a potential, it represents a difference in charge, the strength of attraction between two opposite charges. Different types of batteries use different types of chemical reactions to generate that charge potential difference. The oldest type of battery, and the one we still use on our robots, is the [https://en.wikipedia.org/wiki/Lead%E2%80%93acid_battery lead-acid] battery which uses lead terminals and sulphuric acid. |
