Many years ago, when the use of instrumental music was growing, trumpets became very important. Trumpets were long and without valves. This meant a player had to control the pitch of the sound with only his mouth, which was very difficult. Everyone respected trumpet players because trumpets were just so difficult to play.
The chromatic trumpet was developed in the late 18th century. In the 19th century, good valves made it easier to play notes on the trumpet. Still, trumpet is a difficult instrument to master.
Classical music is written for solo trumpet, and trumpets are included in orchestras. Trumpets play an important part in Jazz music, and other various popular genres. Sometimes, they also play short parts to emphasize sections in rock songs.
Some famous classical trumpet players are Adolph Herseth, Sergei Nakariakov and Maurice Andre.
Some famous jazz trumpet players are Miles Davis, Louis Armstrong, Arturo Sandoval, Wynton Marsalis, Dizzy Gillespie, and Maynard Ferguson.
Microwave
A microwave is a high-frequency radio wave. They are broadly defined as having a wavelength between 1 millimeter and 1 meter, or narrowly between 3 mm and 300 mm. Microwaves have many uses including radar, radio astronomy, and to heat food in a microwave oven. Unlike longer radio waves, they do not bend around land obstacles but go in line of sight. Still, they are much used for communication because they can have a high bandwidth. Almost all spacecraft communicate by microwave radio.
When something moves, it almost always has a wave pattern to its movement - this can be seen in water most easily, in ripples and ocean waves. A very common type of wave in the universe is electromagnetic waves. Light is an example of an electromagnetic wave, and so is a microwave, for example the cosmic microwave background radiation. We can only see electromagnetic radiation in the visible light spectrum (which is why it's called the visible light spectrum), so microwaves are invisible.
Microwaves were among the first radio waves discovered, in the late 19th century, by Heinrich Rudolf Hertz.
Microwave ovens work because microwaves make polar molecules (molecules that act like tiny magnets) all face the same direction - to visualize it, imagine that the microwave oven is telling all of the molecules to face left, then right. Heat is just the movement of molecules, so when the molecules do a great amount of moving, they are hot.
Like other heat sources, microwave radiation can cause burns. They can go through skin and muscles. If vital organs are burned, the burns can kill. This is why a microwave oven does not work with the door open.
Microwave oven
A microwave oven (commonly called a microwave) is a machine that cooks food using microwaves, a type of radio wave. The idea was invented when a scientist who was experimenting with radio waves saw his chocolate bar, which was in his pocket, had melted. He then knew that radio waves could cook food and invented the microwave oven.
The microwave oven uses a magnetron. This is similar to a radio transmitter. It makes very short radio waves which go into the food to a depth of about 2.5cm (one inch). This makes water molecules twist about 2.5 billion times a second. This heats up the molecules around it. As they heat up the heat goes to the inside of the food. This process is called conduction. This also happens in a normal oven, but microwave energy goes deeper so that the food cooks much faster. In an ordinary oven the energy stays mostly near the surface, so it takes more time.
Apart from this, the oven has a wave guide, turntable, and a timer switch. When we place the food inside the chamber and turn the timer switch on, it sends a command to the magnetron to send microwaves, as well as to the turn table to start turning. The microwaves of microwave ovens can heat foods containing polar molecules, such as water, as polar molecules are prone to the vibration effect caused by the microwaves. To heat the food evenly the microwave's turntable spins the food around.
Metals tend to spark in microwaves, rather than heating. The reason why is that metals like to give away electrons, so when the microwaves "push" at their magnet-like electrons, instead of turning, they just give the electrons away. A bunch of electrons running off of metal is called electricity, and we see it in the form of sparks.
Cobalt
Cobalt (chemical symbol Co) is a chemical element. It has an atomic number of 27 and an atomic mass of about 59. It is a metal.
Cobalt is a transition metal. It is shiny and conducts electricity. It is magnetic. It is a hard metal. It is moderately reactive. Iron is more reactive and copper is less reactive. It dissolves slowly in acids. This reaction makes hydrogen and a salt of cobalt. Cobalt is normally in its +2 oxidation state as an ion. Some chemical compounds contain cobalt ions in its +4 oxidation state. Cobalt(II) chloride is one of the most common cobalt compounds. Many cobalt compounds are blue or pink. One of them is black.
Cobalt comes in two oxidation states, +2 and +3. Most soluble cobalt compounds are red. They can also be green, blue, brown, and black.
Cobalt is too reactive to occur as a pure element in the earth. It is found in certain minerals. It is found with copper and nickel deposits. Normally the three metals are bonded to arsenic and sulfur. The majority of cobalt mining is in central Africa.
It is found as a byproduct (left over substance) when copper and nickel are produced. It is made by reaction with the sludge from copper and nickel processing.
Cobalt is used in some types of steel. It hardens the steel. It is also used to make very strong tough alloys. These alloys are known as superalloys. Some cobalt compounds are used in the lithium-ion battery. Cobalt compounds were used as an artificial food coloring until 1971. It was discovered that it has harmful effects. It is used to make glass blue. It is also used as a catalyst. It is also used in some medicines.
The human body needs small amounts of cobalt for certain vitamins. Cobalt compounds are used to stop cyanide from poisoning the body.
People need cobalt compounds in small amounts, but cobalt is toxic in large quantities. Sometimes cobalt compounds were added to beer, and people that drank it were poisoned. It can cause skin irritation when touched.
Canidae
Canidae is a family of carnivorous and omnivorous mammals of the order Carnivora. Animals that belong to the family Canidae are called canids. The family Canidae is divided into two tribes: Vulpini ("true foxes"), and Canini ("true dogs").
Canids of the tribe Vulpini (foxes) are called "vulpines". Canids of the tribe Canini (wolves, dogs, coyotes and others) are called "canines". Some people call all these canids "canines", but this is wrong.
Examples of canids are dogs, wolves, foxes, coyotes, and jackals.
Nickel
Nickel (chemical symbol Ni) is an element. It has an atomic number of 28 and an atomic mass of about 58.69amu. It has 28 protons. It is a transition metal.
Nickel is a silver-white metal. It is easily polished (made shiny). It is magnetic. It is not magnetic when heated above . It is not soft like many other metals. It can be stretched into wires easily. It is not radioactive.
Nickel is not a reactive metal. It dissolves slowly in acids. It does not rust like iron. It makes a thin coating of nickel(II) oxide which stops more corrosion. Aluminium does a similar thing.
Nickel is found in two oxidation states: +2, nickel(II); and +3, nickel(III). Nickel(II) is more common. Nickel in its +2 oxidation state is green. Nickel(II) chloride is a common +2 oxidation state compound. Nickel(II) oxide is normally dark green, but sometimes it is gray. This is because some of the nickel is in the +3 oxidation state (nickel(III). Nickel(III) compounds are oxidizing agents. They also are grayish. Nickel compounds can be green, blue, gray, or black.