In this video, we will show you a massive neodymium permanent magnet assembly weighing
more than half a ton.
This magnet made of rare earth elements represent the strongest class of permanent magnets.
In this video, we first will see what happens when you approach it with ferromagnetic materials
(like steel) and then afterwards we will explore how conductive metals behave in a strong magnetic
Here is a wrench and a scale for measuring the pull of magnet which reaches 25 kg while
the wrench itself is only 1 kg.
On larger ferromagnetic objects attraction can easily reach hundreds of kilograms.
Next up is a hammer!
Note that I added 5 cm (2 inches) layer wood so not to damage the surface and to be able
to "easily" remove it.
Even with this added distance pull force is around 40 kg.
Afterwards, a flexible iron sheet is placed to the magnet which illustrates the distance
where objects are visibly attracted.
The permanent magnet of such size is stronger than earths magnetic field in a radius of
4 meters around it and can turn screens of a laptops from 1.5 meters away
Ferromagnetic objects from iron are drawn to magnet form half a meter away as illustrated
with iron sheets.
We continue experiments with placing a ferrofluid on the magnet.
This reveals the spikes on the surface.
These spikes are acting (pointing) like magnetic field lines so in a sense you can visualize
the magnetic the direction and strength of magnetic field.
Sometimes the camera loses focus because of the strong magnetic field interferes with
electronics and sensors.
The ferrofluid contains very tiny magnetite particles, which acts as tiny magnets and
when the external field is applied they aligned in “spiky” structures pointing in the
direction of the magnetic field vector.
When in close proximity to poles the magnetic forces dominate over gravity making so the
fluid can defy gravity.
If I were to let, go the container it would fly towards the pole of the magnet to the
spot with the highest magnetic field intensity.
Next up we take 4 kg copper sheet and when we throw it towards the magnet it rapidly
When the plate is getting closer to the magnet it moves noticeably slower.
All that happens because of the induced current in the copper sheet.
Copper is an excellent electrical conductor and when it is moved in a magnetic field,
the changing flux creates eddy currents according to the Maxwell’s-Farady’s law of induction.
In short, these currents create an opposing magnetic field and overall damps movement
of copper and that is why it is extremely difficult to move the copper sheet next to
And this simple demonstration perfectly showcases the effect opposing forces caused by induction.
Normally plate of such size would fall down in a second, however, since it is placed in
a strong magnetic field (which changes in plate during fall) it takes almost 20 seconds
for it to hit the ground.
In the end for a bigger effect, we took a 20 kg copper sheet and rolled it in a cylinder
and which we dropped on the magnet.
The first attempt was with a couple of centimeter gap.
The copper sheet is slowed down up until it reaches the center of the magnet.
At that point, the magnetic flux becomes negative and current changes direction.
In the second attempt, we shrunk the gap to 5 mm.
In both cases, it is overwhelmingly slowed down by induced currents.
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