AA, AAA, C, and D cells, including alkaline batteries, are of standard sizes and shapes, and have about 1.5 volts. The voltage of a cell depends on the chemicals used. The electric charge it can supply depends on how large the cell is, as well as what chemicals. The charge a battery delivers is usually measured in . Since the voltage stays the same, more charge means a bigger cell can supply more amps, or run for a longer time.
The first battery was invented in 1800 by Alessandro Volta. Nowadays, his battery is called the voltaic pile.
In small, modern batteries, the fluid is immobilized in a kind of paste and everything is put in a sealed case. Because of this case, nothing can spill out of the battery. Larger batteries, such as car batteries, still have liquid inside and are not sealed. A kind of battery that uses molten salts as the electrolyte was invented during World War II.
Fuel cells and solar cells are not batteries because they do not store the energy inside them.
A capacitor is not a battery because it does not store the energy in a chemical reaction. A capacitor can store electricity and create electricity much faster than a battery, but it usually costs too much to make it as big as a battery can be. Scientists and chemical engineers are working to make better capacitors and batteries for electric cars.
Small electrical generators operated by hand and foot can supply power in small electrical devices. Clockwork radios, clockwork torches and similar devices also have a wind-up spring to store mechanical energy.
Knife
A knife is a metal tool with a sharpened metal blade that is used to cut all sorts of things. The plural form of "knife" is "knives."
There are many kinds of knives, depending what is to be cut. With the right knife, the cuts you want to make will happen faster and more easily. With the wrong kind of knife, it will take more effort to perform the same amount of work. When a knife is too small to cut something, a saw, axe, or power tool may be needed.
Carrying knives is illegal in many countries, especially if the blade is longer than several inches. Another type of knife which is illegal in many places is the "switchblade," a knife that has a button which when pressed activates a spring to open the knife.
Nyngan, New South Wales
Nyngan is a town in New South Wales, Australia. It is built on the banks of the Bogan River. It is north west of Dubbo, and south east of Bourke in the Central West Plains of New South Wales. It is a town of 2500 people. It exists because of the people who work on the farms and in a copper mine, 50 kilometres to the west.
It remains also well known as one of the last depots of Cobb and Co, the famous inland transporter of the 19th century (1801 to 1900). One of the overnight depots was at Nyngan because it is about half way between Dubbo and Bourke. In the days of Cobb and Co, the trip from Dubbo and Bourke would have taken at least 4 days.
However, the route they took is not the route that is used today. The new route runs beside the railway. The railway is a direct line from Dubbo to Nyngan. There is not a single bend for almost 160 kilometres. In the other direction, the track goes 190 kilometres dead straight the whole way to Bourke.
Film (disambiguation)
Film may refer to:
Photographic film
Photographic film is a sheet of plastic used to record pictures. The plastic has been specially treated, so it is sensitive to light. That way, it is possible to record an invisible image with the plastic when it is exposed to light. Normal film is shipped in small canisters (boxes) that protect it from the light. A normal photographic film can hold up to 40 pictures.
Once all pictures have been recorded, the film has to undergo a special chemical treatment. This is called "developing a film" or Film processing. That treatment makes the pictures visible (you can see them), and the exposed film is no longer sensitive to light.
Different kinds of films exist. Some require more light to be exposed than others. Some are black and white only; they record no colors. There are also special films which can record infrared light.
Films also come in different sizes. 35 millimeter film, the most used size, comes in metal cans or canisters, but there are other camera films that come in paper wrappings or in single sheets.
Film can only be used once. After that, it cannot be used again (if it is accidentally used again, this results in an artifact called a multiple exposure). When not in use, film needs to be covered from light, otherwise it will record any lights that shine on it. This will make it useless to record a picture. Film comes in a can called a canister to cover it from light rays.
Film needs the right amount of light to make a picture. If the picture is too bright or too dark, it will not record correctly. The longer that the film keeps recording, the more light it will get. If what is being photographed is bright, it will be recorded faster. If it is darker, the film will need more time to record.
Films that need less time to record the picture are known as "faster" films. Different speeds of films are marked with an ISO number. The higher the number, the faster the films. Films can only make a picture from focused lights. If there is no lens to focus light, the film will only turn white from receiving just the light. If a film with an ISO level of 200 instead of 100 is used, it will only need half as much time to record a picture of the same scene.
Examples of ISO numbers are ISO 50, ISO 100, IS0 200, ISO 400, ISO 800, and ISO 1600. The ISO number is sometimes called the <nowiki>"ASA number" or the "film speed"</nowiki>. When the ISO number is low, for example ISO 50, the film takes a long time to record the picture. This is called a slow film. This means the shutter has to stay open for a long time. When the ISO number is high, for example ISO 800, the picture is made in a very short time. This is a fast film. This means the shutter has to open and close quickly.
Before photographic film was invented, photography used glass dry plates. In the 21st century, most cameras don't use film anymore.
Compass
A compass is a navigational tool that uses magnetism. It has an arrow which points in the direction of the North Magnetic Pole. A compass is very useful for navigating on oceans and in deserts, or other places where there are few landmarks.
The first compass was invented by ancient Chinese in the Han Dynasty. It was a large spoon-like magnetic object made of magnetite ore set upon a square bronze plate.
Ferdinand Magellan
Ferdinand Magellan (1480 – 27 April 1521) was a Portuguese explorer. He became the first European to sail the Pacific Ocean, and the first to sail around the world. Magellan's voyage proved that the Earth was round.
Born in 1480, his birthplace is recorded as either Sabrosa or Porto in Portugal. He worked in the royal court. Since his parents were members of the Portuguese nobility and after their deaths, Magellan became a page for the queen at the age of 10. In the royal court where he learned many important skills, including map making, navigation and astronomy. In 1505 he joined the navy. When he worked for Portugal, he went to many parts of the world, such as India, the Spice Islands, East Africa, and Morocco. When in Morocco in 1513 Magellan was wounded, and walked the remainder of his life with a limp. After he lost his job for the King of Portugal, he went to work for the King of Spain.
He was also the first to sail through the Strait of Magellan, so it was named after him. Magellan himself was killed in the Philippines, on 27 April 1521 in Mactan during a battle with the natives after he was accused of stealing.
Charles V of Spain provided him with five ships for the voyage round the world. Only one ship, the "Victoria", completed the voyage.
Henry the Navigator