Category Science

What is reindeer moss?

Reindeer moss is a species of lichen so called because it is the staple winter food of reindeer (and caribou) in Arctic and Sub-Arctic regions. The animals reach the plant by scraping away the snow with their feet. But Plant growth in those cold northern lands is so slow that the lichen can take more than 30 years to recover after the reindeer have grazed. These domesticated herds therefore have to travel long distance in search of food, and the Laplanders of northern Scandinavia, who depend on the animals for their livelihood, must travel with them.

      Fortunately, reindeer moss is especially abundant in Lapland, although it also grows extensively in much of northern Europe, the tundra (or treeless plains) of Siberia and the barren expanses of Arctic America.

     During the short summer the reindeer are able to feed on herbage and shoots then accessible in the valleys. These versatile animals provide the Laplanders with meat, milk, cheese and the raw materials for clothing, shoes and tents. They are also a means of transport.

     Reindeer moss is sometimes eaten by human beings, after being powdered and mixed with other food. But it leaves a slightly burning sensation on the human palate. This bluish-grey plant grows erect in tufts, and is remarkable for its many branches, which, strangely, resemble a deer’s antlers.

Why are horses measured in hands?

Before man invented rulers and tae measures he often used his hands and feet to express the size of things. An old book published in 1561 says: “Fouregraines of barley make a finger; foure finger a hande; foure hands a Foote”.

     Today horses are still measured in hands. The measurement is taken from the ground to the withers, which is the highest part of the back lying between the shoulder blades.

A hand is reckoned to be four inches, the assumed width of a man’ palm. Formerly it was taken as equal to three inches, when a man’s hand was smaller.

    Early horses were probably around 12 hands (48 inches) at the withers, and one measuring 14 hands was exceptional. Some modern horses, however reach 17 hands and occasionally 20 had. A small horse under 14.2 hands is called a pony.

Magnetism

 

 

How can a train float in the air?

Some experimental trains have been made to float a few centimeters above the ground by using a system of electromagnetic coils embedded in the track. Electromagnetic force can also be made to propel these trains. They have no wheels, so there is very little friction to waste energy. This magnetic propulsion system, which is completely silent, is called magnetic levitation.

Picture credit: google

 
 
 

 

 

How do animal make use of magnetic forces?

Many animals migrate for very long distances, but they arrive back at their birthplace in order to breed. This behaviour has puzzled scientists for many years, but they have now found that many of these creatures contain tiny particles of magnetite in special organs, allowing them to orientate themselves accurately.

Magnetic navigation alone is not enough to account for the amazing ability of these animals to find their way over vast distances. It is thought that they also use other navigation aids, such as the position of the Sun, to help them.

Picture credit: google

 

Magnetism

Magnetic motors

One of the most important uses of magnets is electric motors, which are used to power machines ranging from small toys to enormous railway engines. Video and audio tape recorders also depend on magnetism. Their tapes contain tiny metal particles that are magnetized by the recording heads. When played back, another part of the head decodes the magnetic patterns. The hard drive and floppy disks in a computer work in a similar way.

Picture credit: google

 
 
 
 
 

 

What are magnets made of?

Permanent magnets are usually made from mixtures of iron, cobalt and nickel, but others contain far more complicated mixtures of metals. Magnetite is a natural magnetic substance, which used to be called lodestone. It is a material that contains iron, and it was originally used to make the first primitive compasses.

Picture credit: google

 

 

 

 

 

What is an electromagnet?

Electromagnets only produce magnetism when an electrical current passes through them. They usually consist of a metal core made of iron or a similar material, around which are wrapped many coils of thin insulated wire. The metal core becomes magnetized when an electric current passes through the wire coil, but the effect disappears immediately the current is shut off. Very powerful electromagnets can be created by using many coils and strong electrical currents.

Picture credit: google

 

Magnetism

Is the Earth a magnet?

The Earth is actually a huge magnet, with a magnetic north and a magnetic south pole. These poles are not quite the same as the true geographical poles, and they wander about slightly. There is geological evidence that the magnetic north and south poles sometimes switch their positions completely. The reasons for the Earth’s magnetism are not really understood, but it is thought to be due to the movement of electrical charges around the Earth’s core, which is probably mostly made up of iron.

The Earth’s magnetic field extends out into space. The Sun and the other planets in the Solar System also have magnetic fields. Some distant stars are known to have exceptionally powerful magnetic fields.

Picture credit: google

 
 

 

 

How does a compass work?

The magnetized needle of a compass tries to align itself towards the Earth’s field of magnetic force. The magnetized needle balances on a pointed pin or floats on oil to allow it to rotate freely and to reduce friction. A compass needs to be used with care, because if it is near any object that can distort the Earth’s magnetic field it will give a false reading. A nearby object made of iron or steel, or any source of electrical power, will cause the compass needle to swing wildly.

Picture credit: google

 

Magnetism

 

 

Why do some metals stick to magnets?

An ordinary magnet has two poles, which are usually referred to as the North Pole and South Pole. Similar (like) poles repel each other, while unlike poles attract each other. You can easily see this happening if you hold two magnets close together. The north pole of one magnet will stick firmly to the south pole of the other magnet, while any two similar poles will be forced apart.

Picture credit: google

 

Which substances are magnetic?

Iron, steel and nickel are magnetic substances, that is, they can be attracted by another magnet. Once these materials are in a magnetic field, they act as magnets themselves because the electrons in their atoms become aligned along the magnetic lines of force. This means that you can pick up a whole string of paperclips attached to a single magnet. Once the first paperclip is separated from the magnet, the whole string will collapse because the paperclips are only temporarily magnetized.

Picture credit: google