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Feedback Comments on Magnetism

by Ron Kurtus

A total of 673 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

Topic

Title

Country

Moving Charges Create Magnetic Field How is magnetic field created? India
 
General Device using small disc magnet Canada
 
Solenoids Solenoid and electromagnet India
 
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
 

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How is magnetic field created?

Topic: Moving Charges Create Magnetic Field

Question

November 7, 2017

how megnetic field created around electric current

ravi - India

28312

Answer

Electrical charges have an electric field around them. When the charges move a magnetic field is created perpendicular to that movement. An electric current consists of moving electrical charges.

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Device using small disc magnet

Topic: General

Question

September 6, 2017

Good morning Ron. My son and I are developing a low tech medical device that relies on the attraction between a small disc magnet 20 mm x 2 mm and a similarly sized flat washer. We're having a problem with the amount of attraction between the two and need to increase it and are thinking about increasing the size of the magnet or the washer but are constrained in doing this due to physical dimensions. Is there anything readily available such as a flat washer or disc with a higher than normal iron content that would cause the magnet to be more strongly attracted to it? Many thanks!

Niall - Canada

28214

Answer

You might try a Neodymium disc magnet. They are small, strong and inexpensive and can be bouht through Amazon.com or other outlets.

I hope that helps. Best wishes for success with your device.

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Solenoid and electromagnet

Topic: Solenoids

Question

June 13, 2017

Why solenoid is used for making electromagnet

Nishant - India

28091

Answer

A solenoid is an electromagnet without the iron core in it. The solenoid can be used to pull a core inside it.

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Questions on electromagetism

Topic: Basics of Magnetism

Question

February 17, 2017

DC Electromagnet.
1. Ratio of Core area & Poles face area.
2. What is ATTRACTION POWER?
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
ELECTRO-PERMENANT MAGNETS

tks. rgds, Vish

Viswanatan - India

27886

Answer

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

Question

February 14, 2017

How electromagnet works in railway signals?

Harsh - India

27879

Answer

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

Question

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

27857

Answer

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

Question

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

26934

Answer

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

Question

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

26903

Answer

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

Question

March 2, 2016

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

- India

26831

Answer

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

Question

March 1, 2016

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

faty - Senegal

26825

Answer

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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