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Answers to Readers' Questions on Physical Science:

Magnetic Materials

The following 29 comments and questions have been sent in. They are listed according to date.

List of first 10 items

• What are semi-conductors?
• Can ferrous subtancess be attracted to a magnetic field ?
• Measuring temperature of mercury in a field
• How can we produce electricity from magnet.?
• Why isn't stainless steel magnetic?
• Another way to levitate bodies?
• Magnetic field above the Curie temperature
• Levitating in Earth's magnetic field
• What causes diamagnetic and ferromagnetic properties?
• Difference between conductor and ferromagetic

Next 10

What are semi-conductors?

Question

August 29, 2009

can you please tell me what are semi-conductors and can you explain electromagnetism

asra - Pakistan

18223

Answer

Metals such as Copper are good conductors of electricity. A semi-conductor is a material like Silicon that is only a fair conductor of electricity, but it can have special properties, such as an external electrical field changes the semi-conductor's resistivity. Many devices such as transistor, solar cells, radios and telephones use semi-conductors.

See our lesson on Electromagnetism for information on that subject.

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Can ferrous subtancess be attracted to a magnetic field ?

Question

August 5, 2009

can ferrous subtancess be attracted to a magnetic field if this material are fine grains i have seen a more than weird dust e die

Gratten - USA

18114

Answer

One demonstration of magnetic fields is using fine grains of either in or other ferrous substances to outline the magnetic field. But since he's fine grains also become miniature magnets, sometimes unusual effects can result from their interactions.

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Measuring temperature of mercury in a field

Question

July 27, 2009

i am doing one experiment, in this mercury is flowing through ss-316 which is having 150 degree centigrade temperature, in the presence of 2 Tesla magnetic field, i want to measure temperature in this environment, please give me idea for selection of prorer material (Type K --- Chromel ( Nickel-Chromium Alloy ) / Alumel ( Nickel-Aluminium Alloy))OR Type T --- Copper / Constantan, PLATINUM RTD.

SRINIVAS - India

18066

Answer

An infrared thermometer, which could take readings at a distance may work. But unfortunately, this subject is beyond the scope of our material.

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How can we produce electricity from magnet.?

Question

July 17, 2009

how can we produce electricity from magnet.

chrispus - Kenya

18035

Answer

See the lesson at electrical generation

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Why isn't stainless steel magnetic?

Question

February 10, 2009

Why stainless steels are not magnetic even though they contain Fe & Ni?

- India

17243

Answer

Stainless steel is an alloy of Fe and Ni, which means they are mixed in a molten state. This sets their magnetic domains, so that the material cannot be magnetized. It is a special characteristic of stainless steel.

For more on that, see: http://www.school-for-champions.com/science/magnetic_factors.htm

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Another way to levitate bodies?

Question

May 29, 2008

¿existe otra forma de levitar cuerpos ya sea por rotacion u otros fenomenos?

william - Peru

16006

Answer

Question: Is there another way to levitate bodies either by rotation or other acts?

Answer: Magnetic levitation concerns materials that repel a magnetic field or with magnets of the same pole.

Levitación magnética se refiere a materiales que repeler un campo magnético o con los imanes del mismo polo.

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Magnetic field above the Curie temperature

Question

February 25, 2008

I think I have a good question.

If after hitting the Curie point the material looses magnetic properties wouldnt that mean only the earths outer crust produces the entire north/south magnetic properties that encompass the earth.

Same goes for the sun except I could see electromagnetics being one of the many energy products of the fusion process.

Mike - USA

15431

Answer

That is a good question. The Curie point is the temperature that ferromagnetic materials lose their magnetism because all their domains become misaligned. See: http://www.school-for-champions.com/science/magnetic_factors.htm for information on domains.

Matter inside the Earth and the material on the Sun are in the plasma state of matter, where atoms are ionized and many free electrons exist. The rotation of the body causes these charged particles to act as a magnetohydrodynamic generator where electrical motion causes a magnetic field which in turn creates more electrical motion.

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Levitating in Earth's magnetic field

Question

February 19, 2008

Dear School for Champions,

I need to know if their is a magnet out their that pulls away from earth, and if their was, would a huge enough magnet be able to somewhat hover in mid air, or maybe if there is a way one could somewhat design a magnet that could push away from earths gravity, I would really appreciate the feedback.
I’m doing research on a project and I looked around on the net for information and I came across your site then I thought maybe I could e-mail you for a couple of questions that i need answered.

Thank you and have a great day

Lee - Canada

15396

Answer

There are paramagnetic materials that work the opposite of regular magnets and can be levitated in a magnetic field. But the force is very weak and needs a strong magnetic field to work. The Earth's magnetic field is weak compared to a standard magnet, so levitation in the Earth's field is unlikely.

See: http://www.school-for-champions.com/science/magnetic_materials.htm

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What causes diamagnetic and ferromagnetic properties?

Question

February 4, 2008

what is responsible for diamagnetic and ferromagnetic property?
Why is even atomic no. molecule mostly diamagnetic?

priyanka - India

15268

Answer

Electrons rotating in orbit create a magnetic field. The ferromagnetic effect is caused by alignment of atoms so that the field is strong. With diamagnetic materials, the electrons are going in the opposite direction, and thus are repelled by a standard magnet.

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Difference between conductor and ferromagetic

Question

December 12, 2007

My questions are:
1. what are the differences between common conductor materials and ferromagetic materials?
2. what are the differences when a common conductor moves in the magnetic field and when a ferrite moves in the magnetic field?

jimmy - Thailand

14968

Answer

Copper and aluminum are common electrical conductors, but neither is magnetic because their atoms do not line up properly. Iron and nickel are ferromagnetic materials, and thus they can be magnetic. But note that both iron and nickel also conduct electricity.

When any electrical conductor moves through a magnetic field, an electrical current is caused in the conductor. But when a ferromagnetic material such as an iron wire moves through the magnetic field, it not only conducts electricity, but its atoms also line up, making the material magnetic. This may hinder its conduction of electricity.

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