Where can I find magnet blockers?!?

Question

Hi, I'm curious is there anything that can block a magnet (stop it moving stuff on the other side of the object) and where can I buy it?

also can anybody tell me where i can find 2-3inch balls that will stick to magnets

Answer 1

No big deal - a plate of soft iron or other high-µ metal will confine the magnetic field within itself and stop it reaching the other side.

Answer 2

Magnetic fields can't really be blocked easily. You can however do it two ways:

Firstly by active canceling-

For example by placing another magnet nearby aligned so both are repelling each other. Then somewhere (about halfway in between if they are the same) both magnetic fields will cancel each other.

Secondly passively canceling.

You can use materials that magnetic flux flows easily through (like iron) to direct the magnetic field away from an area. For example putting a big bit of iron between the poles of a c shaped magnet will weaken the field a little distance away. This type of shielding requires some skill (or magnetic field modeling programs) to get right.

It is unfortunate that magnetic fields are so difficult to block as this is one of the things that makes hospital MRI scanners expensive.

Magnetic leakage is the reason why people with implants sensitive to magnetic fields (like a heart pacemaker) can't go anywhere near MRI machines even well shielded ones.

Finally,

Engineering workshops might sell you big ball bearing that would stick to your magnets. If you really want you can actually buy 2-3inch incredibly strong sphere magnets at wondermagnet. They really will stick to your magnets and you'll do d**n well to get them back off.