Magnets and magnetic fields are part of the natural world. Playing with magnets are often the first introduction to science that kids experience. The earth is magnetic due to the fact that it contains rocks such as iron that are rich magnetic materials. It is also believed that the earth’s core is made of iron, which causes the magnetism.
The magnetic field of earth stretches out over the entire planet and into space. The earth’s magnetic field is called the ‘magnetosphere’ and it acts as a protection for the earth.
- Energy, including the sun’s energy, hits the earth are filled with zooming particles. When it is from the sun it is called the ‘solar wind’. When the suns energy hits the magnetosphere of earth and bounces off, we can see it happening in the sky with the amazing colors of the ‘auroras’.
- There are different types of ‘auroras’: the aurora borealis or ‘northern lights’ and the aurora australis or ‘southern lights’. These are all visuals of the sun bouncing off of the earth’s magnetosphere.
The magnetic field of the earth isn’t actually that strong. It is about 1,000 times weaker than that of a magnetic bar that you might experiment with.
- The reason that we don’t fly off into space is due to gravity, not magnetism. If the earth didn’t have gravity we would be able to feel the effects of magnetism more.
- We know that other planets in the solar system have magnetic fields and some, like the moon, has little or none at all.
- Magnets have polar ends: positive and negative, also called ‘north’ and ‘south. When two of the same type are put together they ‘repel’ or push away. When two opposites (a positive and a negative) are put together, they attract each other.
The magnetic strength of a field really depends on how close you are. The strongest magnetic areas are very close and the strength begins to weaken as you move away.
Most metals that we are familiar with are not attracted to magnets. This can include gold, silver, aluminum, copper, magnesium and platinum.
Magnetic fields cannot be seen with the human eye. You can do an experiment by placing metal chips that are attracted to magnets around each pole. They will align themselves up in a pattern that displays the strongest and weakest areas of the magnet.
The measurement of a magnetic field is in units that are called ‘gauss’ and ‘Tesla’. The Tesla is named after the pioneer in electronics, Nikola Tesla.
- A magnet compass makes use of the magnetic field of the earth so that the arrow points the directions of north, south, east, west and all of the variations of these directions.
- Scientists in the 19th century discovered that magnetism flows through electricity. Each time an electric current flows, it creates a magnetic field.
Electromagnets can be easily created by running an electric current through a surrounding coil. This is called a ‘solenoid’. They have the ability to turn the magnetic field on and off through the use of the electric current. We use electromagnets in everyday life including the door chimes at a house. The larger electromagnets are used to generate electricity at hydroelectric dams.
- The use of magnetic fields with generators and an energy source such as wind, water and steam, can create electricity.
- The magnets that you might have on your refrigerator are called ‘permanent magnets’. They hold their magnetic field full time.