Different methods of strengthening a magnetic field.

• gramps1
In summary, the electromagnet can produce a weak magnetic field that can be felt by the hand. The field can be increased by adding a pole piece to the coil, and by reducing the air gap.
gramps1
Hello!
Lately I've been experimenting with the ways an electromagnet effects a Rare Earth magnet. The electromagnet we used was taken from a vibrator massager, probably 50s vintage. The resistance of the coil is 96 ohms and consumes about 1.25 amps when operated on 120 volts AC. When the electromagnet is energized, a small Rare Earth magnet will vibrate (probably in harmony with the 60 hertz AC). If the magnet is held in the palm this vibration can be felt as far as 12 inches from the coil. However the coil runs hot and is burning a hot of amps.
How can we reproduce this effect with a different coil and or power supply design that only uses perhaps 125 milliamps?
Thanks, Gramps

You'd have to give a sketch of your setup, so that we can see what kind of solenoid/motor you are trying to make.

Wire a 25W incadescent light bulb in series with the electromagnet. This will limit the current.

Hi FinBurger,
I hope this will suffice for a sketch
Photo of the electromagnet.

The experiment consists of holding a rare Earth magnet 10 inches above the electromagnet and noting the extent of the field by feeling the magnet's vibration in the palm of the hand.
Tom.G,
We will try that but I think it would reduce the magnetic field.
Edit we want to .maintain the same field strength but use less power.

Last edited:
FIeld Strength: directly proportional to Current x Turns

Modified of course by the material used for the core, and, as others have mentioned, the dimensional aspect ratio of the windings.

gramps1 said:
Hello!
Lately I've been experimenting with the ways an electromagnet effects a Rare Earth magnet. The electromagnet we used was taken from a vibrator massager, probably 50s vintage. The resistance of the coil is 96 ohms and consumes about 1.25 amps when operated on 120 volts AC. When the electromagnet is energized, a small Rare Earth magnet will vibrate (probably in harmony with the 60 hertz AC). If the magnet is held in the palm this vibration can be felt as far as 12 inches from the coil. However the coil runs hot and is burning a hot of amps.
How can we reproduce this effect with a different coil and or power supply design that only uses perhaps 125 milliamps?
Thanks, Gramps

gramps1 said:
Hi FinBurger,
I hope this will suffice for a sketch
Photo of the electromagnet.
View attachment 283148
The experiment consists of holding a rare Earth magnet 10 inches above the electromagnet and noting the extent of the field by feeling the magnet's vibration in the palm of the hand.
Tom.G,
We will try that but I think it would reduce the magnetic field.
Edit we want to .maintain the same field strength but use less power.
So, the coil here has a core that is shaped like an "E". The magnetic circuit runs up through the middle arm, has to jump through the air, and then runs down the outer arms to close the loop. The magnetic field feels about 4000 times less magnetic resistance in the iron as in the air. So, to increase your magnetic field, you want to make the air gap smaller.

Add a pole piece of soft iron that almost bridges the gap. You should find that this increases the inductance of the coil, and that will reduce the ohmic (heat) loss.

By the way, when you put the permanent magnet on the core, you raise the possibility of saturating the iron's magnetization, and this makes it a poor magnetic conductor. This will reduce the inductance, and thus increase the ohmic loss (which is what you saw).

Lastly, what is your final goal? If it is to make a vibrator, then you need to optimize the whole electromagneto-mechanical system. That is, the movable mass that the coil will be pulling on should be suspended on a spring such that its resonant frequency (simple harmonic oscillator) is close to 60 Hz.

1. How can I increase the strength of a magnet?

There are several methods for strengthening a magnetic field. One way is to increase the number of turns in the coil of a solenoid. Another method is to use a ferromagnetic material, such as iron, to create a magnetic circuit that concentrates the magnetic field.

2. Can the distance between two magnets affect the strength of their fields?

Yes, the strength of a magnetic field decreases as the distance between two magnets increases. This is known as the inverse square law, which states that the strength of a field is inversely proportional to the square of the distance from the source.

3. What is the difference between permanent magnets and electromagnets?

Permanent magnets have a fixed magnetic field and do not require an external power source to maintain their strength. Electromagnets, on the other hand, use an electric current to create a magnetic field and can be turned on and off.

4. Can magnets be stacked to create a stronger field?

Yes, stacking magnets can increase the overall strength of the magnetic field. However, the orientation and alignment of the magnets must be carefully considered to ensure that the fields are properly aligned and do not cancel each other out.

5. Are there any natural materials that can strengthen a magnetic field?

Yes, some natural materials, such as lodestone and magnetite, have magnetic properties and can be used to strengthen a magnetic field. These materials are often used in the production of permanent magnets.

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