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Feedback Comments on Magnetism

by Ron Kurtus

A total of 670 comments and questions have been sent in. They are listed according to date.

You can read them to further your understanding of the subject.

List of most recent 10 letters




Basics of Magnetism Questions on electromagetism India
Electromagnetic Devices How do electromagnets work in railway signals? India
Electromagnets Placing electromagnet inside another electromagnet USA
Magnetic Materials Srength of neodymium super magnets Philippines
Electromagnetism Why is copper used in a motor's stators? USA
Magnetism Lorentz Applying Lorentz force at the equator India
Magnetic Materials First grade science fair project Senegal
Electromagnetism Used information for research USA
Solenoids Ferromagnetism and solenoids Nigeria
Moving Charges Create Magnetic Field How does electric current create a magnetic field? Nigeria

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Questions on electromagetism

Topic: Basics of Magnetism


February 17, 2017

DC Electromagnet.
1. Ratio of Core area & Poles face area.
3. If three sides of magnet is covered with non magnetic material will there be more force on pole faces.
4. Construction & operation details of

tks. rgds, Vish

Viswanatan - India



See our lessons on Electromagnetism. They should help answer some of your questions.

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How do electromagnets work in railway signals?

Topic: Electromagnetic Devices


February 14, 2017

How electromagnet works in railway signals?

Harsh - India



Railway signals can be flashing lights or a moving barrier.

An electromagnet could be used as a solenoid to turn on or turn off the railway signals.

The barrier is usually moved by an electric motor.

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Placing electromagnet inside another electromagnet

Topic: Electromagnets


February 5, 2017

I have a new found curiosity for electromagnets. I'm not a scientist or even a student... just curious. What would happen if your electromagnet core contained another electromagnet?

Ron - USA



If the core is movable, you would have a solenoid of sorts. (See Solenoids are Electromagnetic Devices).

Instead of having a movable iron core or magnet core, you would place an electromagnet there. This would allow movement of the core to be finely tuned. However, I don't think I've even seen such a configuration.

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Srength of neodymium super magnets

Topic: Magnetic Materials


April 15, 2016

I have 3 pcs N52 neodymium super magnets. How do I know the strength of attraction between the two of them in contact with each other without anything in between, or conversely how strong they will push each other apart it they measure 10 mm x 5 mm x 2 mm, with the poles on the larger faces (5 x 10) and, if the poles are on the smaller faces (5 x 2)?

Junnel - Philippines



Since there is a wide variation on the strength of neodymium super magnets, the best way to find the strength of attraction and repulsion would be to experimentally measure it. For example, you could use a spring scale to measure the force required to pull the two magnets apart.

Other than that, I don't readily know of equations to allow you to predict the forces.

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Why is copper used in a motor's stators?

Topic: Electromagnetism


April 5, 2016

Hi Ron,

My question, if you don't mind, is why do I see copper used if iron in the below stator if they are weak magnets? Cost?

Thanks for the information on your site and for replying to me email if you have the time.

Richard - USA



The stator in an electric motor is the stationary part of the motor’s electromagnetic circuit. It usually consists of copper windings to create the magnetic field.

The copper is much more efficient than using iron wire.

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Applying Lorentz force at the equator

Topic: Magnetism Lorentz


March 2, 2016

is there is a possibility for applying the lorentz force in the earth magnetic field at the equator?

- India



The Lorentz force has been use with wires having from a space vehicle in order to create a current from the Earth's magnetic field.

However, the movement of a wire at the equator would not be enough to create a current.

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First grade science fair project

Topic: Magnetic Materials


March 1, 2016

I work on magnetism for first grade science fair how to win?

faty - Senegal



Your goal in the science fair should be to do your best to show others about magnetism as well as to do an excellent job.

You can demonstrated or show some effects of magnetism. See Magnetism Project: Make an Electromagnet for an example.

Note that it is important to have a display or some sort that others can see.

Best wishes on doing a great job in your project. I am sure you will.

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Used information for research

Topic: Electromagnetism


January 13, 2016

I used this page for research for my science fair project. Don't worry, I did not copy, but I do appreciate this page on electromagnetism.

Kelsey - USA



I'm glad the material was useful to you and your science fair project. It would be good to cite this website, as well as others where you got information in your report. That improves the validity of your experiment.

Best wishes for success in your project.

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Ferromagnetism and solenoids

Topic: Solenoids


January 4, 2016

does ferromagnetism involves a metal core wrapped round with an coil of wire wrapped round it and connected to an electric current if yes isn't this same as a solenoid?

kevwe - Nigeria



A solenoid is simply a coil of wire with no iron core. Current through the wire creates an electromagnetic field. If an iron rod is placed inside the coils, it will be drawn in. That is the concepts of a solenoid switch.
Ferromagnetism concerns forming magnets in iron objects. (Ferro = iron). A solenoid can cause an iron core to become magnetized.

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How does electric current create a magnetic field?

Topic: Moving Charges Create Magnetic Field


December 15, 2015

how does an electric current creates a magnetic field when a current is passed through a wire. what is the process that goes on which causes the magnetic field to be formed by a current.

kevwe - Nigeria



Electric and magnetic fields are tied together, such that when one changes, it causes the other to change. It is a property of matter.

An electron has an electric field, but there is no noticeable magnetic field until the electron starts to move. When the electron moves, it creates a magnetic field, which moves along with it. Thus, a current in a wire is surrounded by a magnetic field.

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