Electromagnetic Force

There are several fundamental forces that hold our universe together.

One of these, of course, is gravity, the force between objects that have mass.

Another important force is the electromagnetic force.

The electromagnetic force is responsible for chemical reactions.

Without it there would be no atoms or molecules.

Up until a couple of hundred years ago, very little was known about this force.

Learning about the electromagnetic force and how to use it was a major step forward.

It revolutionized communication, transportation and manufacturing.

Imagine what life would be like without electricity!

The electromagnetic force has two parts, the electrical force and the magnetic force.

The electric force is the force between electrically charged particles such as electrons and protons.

Electric charges attract or repel each other with a force that depends on the distance between them.

The magnetic force is the force between magnetic poles, such as the north and south pole.

In fact, the Earth is like a large bar magnet, with a north and a south pole.

Many animals use the Earth's magnetic field to navigate during their migrations.

We can also see this magnetic field when we use a compass.

For what purpose do many animals use the earth's magnetic field ? for navigation

Why does the Earth have a magnetic field?

Many scientists believe that the Earth's magnetic field is due to the Earth's rotation.

Deep inside the Earth is a solid iron core, surrounded by a liquid metal outer core.

The moving electric currents inside this liquid metal create a magnetic field.

What is deep inside the Earth? a solid iron core

The Earth's magnetic field is important because it protects us from the solar wind.

The solar wind is a current of charged particles coming at us from the Sun.

When the solar wind nears the Earth, the Earth's magnetic field deflects it away.

This protects the Earth from the radiation, which can be dangerous to life.

It also protects the satellites that we use for communication.

What protects the Earth from the solar wind ? the earth's magnetic field

The Earth’s magnetic field protects the Earth from the solar wind.

Magnetic Field Reversal

Scientists now believe that the Earth's magnetic field is about to reverse.

This is called magnetic field reversal.

Every 200,000 to 300,000 years, the Earth's magnetic field reverses.

In other words, the North and South magnetic poles switch places.

This has happened many times in Earth's history, but it has been happening more lately.

What happens during a magnetic field reversal? The North and South magnetic poles switch places./The Earth's magnetic poles switch places.

Recent research provides evidence that there have been five magnetic reversals during the past 500,000 years.

The most recent event happened approximately 41,000 years ago.

Recent studies have found that the Earth's magnetic field has weakened about 5% per decade.

At its current rate, the next reversal could happen within the next century.

How long is a decade ? 10 years

According to recent research, how long ago did the last reversal occurred ?about 41,000 years ago

Many scientists believe that the Earth's magnetic field is due to the Earth's rotation.

Some people worry about the effects of a magnetic field reversal.

They think there is a possibility that it could cause many problems.

For example, without a magnetic field, communications could be disrupted.

Birds and other forms of life could become confused and get lost.

Another effect would be an increase in some forms of cancer, especially skin cancer.

This would be because of an increase in the amount of radiation absorbed by our bodies.

An increase in radiation causes some forms of cancer.

Why could birds become confused if there were no magnetic field ?They would become confused because they use Earth's magnetic field for

Why are some people worried about magnetic reversal? They think it could cause many problems.

The possibility that a field reversal would be an extinction event is very low.

There is very little historical evidence to show that previous reversals have caused extinctions.

Humans have been on Earth for millions of years, during which there have been many reversals.

Therefore, scientists believe that any changes would be temporary.

Another theory is that the Earth's outer layer could rotate around the liquid metal outer core that makes up most of the earth.

So in the next reversal continents could shift positions, from north to south.

Imagine, if that happened, Australia would be in the northern hemisphere!

If the Earth outer layer rotated around the liquid metal outer core it would cause the continents to shift positions.

How likely is that field reversal would be an extinction event? It's holier? likely.

With so many theories, how can we know what to believe?

This is important because some events require us to act well in advance.

Otherwise it will be too late to prevent a catastrophe.

This underlines the importance of getting reliable information, backed by strong  evidence.

Some events require us to act well in advance to prevent them.