earth as a magnet

kqed illuminating the northern lights

Northern California residents may not be able to see the northern lights like people in Alaska can, but Bay Area scientists are playing a key role in understanding them. Find out more about the spectacular light shows up north and what scientists at UC Berkeley are discovering about the Earths magnetic field. For more information on the northern lights, see http://science.kqed.org/quest/video/illuminating-the-northern-lights/ . MEDIA Click image to the left or use the URL below. URL:

benefits of earths magnetic field

Earths magnetic field helps protect Earth and its organisms from harmful particles given off by the sun. Most of the particles are attracted to the north and south magnetic poles, where Earths magnetic field is strongest. This is also where relatively few organisms live. Another benefit of Earths magnetic field is its use for navigation. People use compasses to detect Earths magnetic north pole and tell direction. Many animals have natural "compasses" that work just as well. Birds like the garden warbler in Figure 24.16 use Earths magnetic field to guide their annual migrations. Recent research suggests that warblers and other migrating birds have structures in their eyes that let them see Earths magnetic field as a visual pattern. You can learn more about animals and Earths magnetic field, including the potential effects of magnetic field reversals, at this URL: .

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why is earth a magnet

The idea that Earth is a magnet is far from new. It was first proposed in 1600 by a British physician named William Gilbert. However, explaining why Earth acts like a magnet is a relatively recent discovery. It had to wait until the development of technologies such as seismographs, which detect and measure earthquake waves. Then scientists could learn about Earths inner structure (see Figure 24.15). They discovered that Earth has an inner and outer core and that the outer core consists of liquid metals, mainly iron and nickel. Scientists think that Earths magnetic field is generated by the movement of charged particles through the molten metals in the outer core. The particles move as Earth spins on its axis. The video at the URL below takes a closer look at how this occurs. MEDIA Click image to the left or use the URL below. URL:

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magnetic field reversals

Do you like to read science fiction? Science fiction writers are really creative. For example, an author might write about a time in the distant past when compasses pointed south instead of north. Actually, this idea isnt fictionits a fact! Earths magnetic poles have switched places repeatedly over the past hundreds of millions of years, each time reversing Earths magnetic field. This is illustrated in Figure 24.13. Scientists dont know for certain why magnetic reversals occur, but there is hard evidence showing that they have occurred. The evidence comes from rocks on the ocean floor. Look at Figure 24.14, which shows a ridge on the ocean floor. At the center of the ridge, hot magma pushes up through the crust and hardens into rock. Once the magma hardens, the alignment of magnetic domains in the rock is frozen in place forever. The newly hardened rock is then gradually pushed away from the ridge in both directions as more magma erupts and newer rock forms. Rock samples from many places on the ocean floor reveal that magnetic domains of rocks from different time periods are aligned in opposite directions. The evidence shows that Earths magnetic field reversed hundreds of times over the last 330 million years. The last reversal was less than a million years ago. What might happen if a magnetic reversal occurred in your lifetime? How might it affect you? You can learn more about Earths magnetic reversals at this URL: .

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earths magnetic field

Like all magnets, Earth has a magnetic field. Earths magnetic field is called the magnetosphere. It is a huge region that extends outward from Earth for several thousand kilometers but is strongest at the poles. You can see the extent of the magnetosphere in Figure 24.12. For an animated version of the magnetosphere, watch the video at this URL: MEDIA Click image to the left or use the URL below. URL:

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earths magnetic poles

Although a compass always points north, it doesnt point to Earths geographic north pole, which is located at 90 north latitude (see Figure 24.11). Instead, it points to Earths magnetic north pole, which is located at about 80 north latitude. Earths magnetic south pole is also located several degrees of latitude away from the geographic south pole. A compass pointer has north and south poles, and its north pole points to Earths magnetic north pole. Why does this happen if opposite poles attract? Why doesnt the compass needle point south instead? The answer may surprise you. Earths magnetic north pole is actually the south pole of magnet Earth! Its called the magnetic north pole to avoid confusion. Because its close to the geographic north pole, it would be confusing to call it the magnetic south pole.

magnet earth

Imagine a huge bar magnet passing through Earths axis, as illustrated in Figure 24.10. This is a good representation of Earth as a magnet. Like a bar magnet, Earth has north and south magnetic poles and a magnetic field.

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instructional diagrams

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This Diagram shows the Earth's Magnetic Field. Our planets magnetic field is believed to be generated deep down in the Earths core. And is created by the rotation of the Earth and Earth's core. It shields the Earth against harmful particles in space. The field is unstable and has changed often in the history of the Earth. The magnetic field creates magnetic poles that are near the geographical poles. A compass uses the geomagnetic field to find directions. Many migratory animals also use the field when they travel long distances each spring and fall. The magnetic poles will trade places during a magnetic reversal.

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This Diagram Shows the earth and how it acts as a magnet. It clearly depicts the geographic north pole and the magnetic north pole. Like all magnets, Earth has a magnetic field. Earths magnetic field is called the magnetosphere. It is a huge region that extends outward from Earth for several thousand kilometers but is strongest at the poles. Evidence in rocks shows that Earths magnetic poles switched positions hundreds of times in the past. Scien- tists think that Earths magnetic field is caused by the movement of charged particles through molten metals in the outer core. Earths magnetic field helps protect Earths surface and its organisms from harmful solar particles by pulling most of the particles toward the magnetic poles. Earths magnetic field is also used for navigation by humans and many other

questions

The north end of a compass needle always points to 90 north latitude.

a. true

-->  b. false

The idea that Earth is a magnet was first proposed in

-->  a. 1600.

b. 1700.

c. 1800.

d. 1900.

Earths magnetic field extends outward from the planet in all directions.

-->  a. true

b. false

The magnetosphere is

a. a huge region.

b. strongest at the poles.

c. the region where Earth exerts magnetic force.

-->  d. all of the above

Earths magnetic poles have switched places many times over the past hundred years.

a. true

-->  b. false

What causes Earths magnetism?

-->  a. The movement of charged particles in Earths outer core.

b. The revolution of Earth around the sun.

c. The magnetism of the sun.

d. none of the above

Evidence for magnetic field reversals comes from

-->  a. rocks on the ocean floor.

b. metals in Earths liquid core.

c. measurements of Earths magnetosphere.

d. seismograph readings from inside Earth.

Once molten rocks harden, their magnetic domains are frozen in place forever.

-->  a. true

b. false

Earths outer core is made up mainly of iron and nickel.

-->  a. true

b. false

Earths magnetic field is beneficial to living things because it

a. protects them from harmful particles.

b. can be used for navigation.

c. never changes.

-->  d. two of the above

Charged particles move inside Earth when it spins on its axis.

-->  a. true

b. false

Harmful particles from the sun are repelled by Earths magnetic poles.

a. true

-->  b. false

Magnetic reversals were discovered by William Gilbert in 1600.

a. true

-->  b. false

Earths south magnetic pole is the same as Earths south geographic pole.

a. true

-->  b. false

Migrating birds may detect Earths magnetic field with structures in their eyes.

-->  a. true

b. false

Earth has north and south magnetic poles like a bar magnet.

-->  a. true

b. false

Like a bar magnet, planet Earth

a. exerts magnetic force.

b. has a magnetic field.

c. has magnetic poles.

-->  d. all of the above

Earths magnetic and geographic poles are located in the same places.

a. true

-->  b. false

Earths true north magnetic pole is actually located near Earths

a. equator.

b. south magnetic pole.

-->  c. south geographic pole.

d. none of the above

Earths magnetic field extends outward from Earth for

a. a few kilometers.

b. about 100 kilometers.

c. about 330 kilometers.

-->  d. several thousand kilometers.

Scientists no longer accept the idea of magnetic reversals.

a. true

-->  b. false

The magnetosphere

a. completely surrounds Earth.

b. is found only near Earths poles.

c. exists over a region larger than Earth.

-->  d. two of the above

Earths magnetic field occurs only over the north and south poles.

a. true

-->  b. false

Earths magnetic force is exerted over a distance.

-->  a. true

b. false

Which statement about magnetic reversals is false?

a. Magnetic reversals have occurred hundreds of times.

-->  b. The most recent magnetic reversal occurred 330 million years ago.

c. There is hard evidence showing that magnetic reversals have occurred.

d. Scientists do not know for certain why magnetic reversals have occurre

The idea that Earth is a magnet was first proposed

a. by William Gilbert in 1800.

b. after seismographs were developed.

-->  c. before scientists learned about Earths inner structure.

d. around the same time that Earths outer core was discovere

Many migrating birds

a. navigate using Earths magnetic field.

b. may be able to see Earths magnetic field.

c. have natural compasses that they use for migration.

-->  d. all of the above

about 80 north latitude

a. magnetosphere

b. north geographic pole

c. outer core

-->  d. north magnetic pole

e. magnetic reversal

f. compass

g. inner core

solid sphere that makes up Earths center

a. magnetosphere

b. north geographic pole

c. outer core

d. north magnetic pole

e. magnetic reversal

f. compass

-->  g. inner core

exactly 90 north latitude

a. magnetosphere

-->  b. north geographic pole

c. outer core

d. north magnetic pole

e. magnetic reversal

f. compass

g. inner core

region deep inside Earth that consists of liquid metals

a. magnetosphere

b. north geographic pole

-->  c. outer core

d. north magnetic pole

e. magnetic reversal

f. compass

g. inner core

Earths magnetic field

-->  a. magnetosphere

b. north geographic pole

c. outer core

d. north magnetic pole

e. magnetic reversal

f. compass

g. inner core

switching of Earths north and south magnetic poles

a. magnetosphere

b. north geographic pole

c. outer core

d. north magnetic pole

-->  e. magnetic reversal

f. compass

g. inner core

navigation device that always points north

a. magnetosphere

b. north geographic pole

c. outer core

d. north magnetic pole

e. magnetic reversal

-->  f. compass

g. inner core

diagram questions

question_image

How does the magnetic north pole align with the earth's magnetic field?

a. Parallel to the geographic north pole

b. Perpendicular to the south polar field line

c. Perpendicular to the north polar field line

-->  d. Parallel to the north polar field line

question_image

How many geographic poles does the earth have?

a. 4

b. 3

-->  c. 2

d. 1

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How many degrees are between the geographic north pole and the magnetic north pole?

a. 10

b. 13

c. 12

-->  d. 11.5

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The magnetic and geographic pole are separated by how many degrees?

-->  a. 11.5

b. 12.5

c. 13.5

d. 10.5

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What is the angle difference between the north magnetic pole and the geographic north pole?

a. 10 degrees

-->  b. 11.5 degrees

c. 12.5 degrees

d. 11 degrees

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How many magnetic poles does the earth have?

a. 4

b. 3

-->  c. 2

d. 1

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The magnetosphere is stronger in some specific areas. Which?

a. Greenwitch

b. The equator

c. The center of the Earth

-->  d. The poles

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Where is the magnetic north pole located?

a. Equator

b. West of the geographic north pole

c. At the rotation axis

-->  d. East of the geographic north pole

question_image

How many poles are represented in the diagram?

a. 3

b. 2

c. 1

-->  d. 4

question_image

How many types of pole are shown?

-->  a. 4

b. 2

c. 6

d. 5

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What is the imaginary line called that divides the earth into northern and southern hemispheres?

a. Magnetic north pole

-->  b. Equator

c. Geographic north pole

d. Rotational Axis

question_image

What is the area between the Sun and Earth wherein solar wind is deflected by Earth's magnetic field?

-->  a. Magnetopause

b. Magnetosphere

c. Solar Wind

d. Van Allen belts

question_image

How many magnetic poles are found on Earth?

a. 4

b. 3

c. 1

-->  d. 2

question_image

How many types of belt are shown in the picture?

a. 1

-->  b. 2

c. 3

d. 4

question_image

How many types of van allen belt are there?

-->  a. 2

b. 4

c. 5

d. 3

question_image

In this diagram about earth as a magnet, which belt occurs beneath Outer van Allen belt?

a. Earth's magnetic field

b. Inner core

-->  c. Inner van Allen belt

d. Outer core

question_image

Which pole is marked red?

a. South geographic pole

b. North geographic pole

c. North magnetic pole

-->  d. South magnetic pole

question_image

What do the blue arrows represent?

a. Lithosphere

-->  b. Magnetosphere

c. Exosphere

d. Ionasphere

question_image

How many magnetic poles does the Earth have?

-->  a. 2

b. 4

c. 1

d. 3

question_image

How many types of magnetic poles are shown?

a. 3

b. 1

-->  c. 2

d. 5

question_image

What is the continuous flow of charged particles from the sun that permeates the solar system?

a. South Connected

b. Magnetosphere

-->  c. Solar Wind

d. North Connected

question_image

How many magnetic poles are found on Earth?

-->  a. 2

b. 1

c. 3

d. 4

question_image

What would happen if the earth polar shifts?

-->  a. the earth's magnetic field will reverse

b. the earth will lose its orbit

c. the earth will spin clockwise

d. the earth will stop spinning

question_image

What is the degree difference between the North Magnetic Pole and the Geographic North Pole?

-->  a. 11.5 degrees

b. South Magnetic Pole

c. Geographic South Pole

d. 2670 degrees

question_image

How many magnetic poles does the Earth have?

-->  a. 2

b. 3

c. 1

d. 4

question_image

How many poles are there in total?

a. 1

b. 3

-->  c. 4

d. 2

question_image

How many degrees is the difference between the earth's north magnetic pole and its geographic north pole?

-->  a. 11

b. 10.5

c. 12

d. 11.5

question_image

Where on this diagram is the earth's magnetic at its strongest?

a. At the geographic south pole

-->  b. At the magnetic poles

c. At the geographic north pole

d. At the equator

question_image

The magnetic field of the earth is similar to a magnetic field of a

a. electromagnet

-->  b. bar magnet

c. disc magnet

d. compass

question_image

How many North poles are there?

a. 4

b. 1

-->  c. 2

d. 3

question_image

How many types of poles are shown?

a. 4

b. 1

-->  c. 2

d. 3

question_image

At which angle is the magnetic north pole and geographic north pole different?

a. 90 degrees

b. 0 degrees

c. 180 degrees

-->  d. 11.5 degrees

question_image

What kind of magnetic field is show on the figure?

a. Reverse

-->  b. Normal

c. Inverse

d. Constant

question_image

How many poles does a magnet have?

a. Four

b. One

-->  c. Two

d. Three

question_image

How many types of poles are shown?

a. 3

-->  b. 2

c. 1

d. 5

question_image

This photo represents the earth's magnetic field. What is the proper term for this magnetic field?

a. toposphere

b. south pole

-->  c. magnetosphere

d. north pole

question_image

What is the next layer underneath the Earth's crust?

a. Outer Core

b. Axis

-->  c. The Mantle

d. Inner Core

question_image

Which part of the diagram shown below is responsible for the Earth's magnetic field?

a. Mantle

b. North Pole

c. Crust

-->  d. Inner Core

question_image

What lies between the outer core and Earth's crust?

a. north pole

b. south pole

-->  c. mantle

d. inner core

question_image

How many parts make up the earth?

a. 3

b. 2

-->  c. 4

d. 1

question_image

How many magnetic poles are found on Earth?

a. 1

b. 3

c. 4

-->  d. 2

question_image

What is the innermost part of the earth called?

a. mantle

b. crust

-->  c. inner core

d. outer core