How far can a strong neodymium magnet be sucked?

Recently, a netizen from Magnet Bar raised a question that caught the attention of the editor. His question is: The specific specifications of the strong magnet I want are as follows: circular or square, with a diameter of 30 to 80 centimeters and a thickness of no more than 5 millimeters. It can suck iron weighing 50 grams from one meter away. Is this possible?  

Is there a definition or standard for how far a strong magnet can attract?

In fact, this question cannot be answered accurately at all. The attraction of a magnet is roughly proportional to the square of the distance. Relatively speaking, the larger the surface area of the magnet, the more magnetic induction lines there are in space, and the distance of attraction is also longer.

In addition, it is also related to the material, weight, and whether there is a non-magnetic material barrier in the middle of the adsorbed object.

Accompanying picture shows block neodymium magnets. To increase the adsorption distance, the size needs to be made larger and thicker.

Usually, the adsorption distance of neodymium magnets is between a few millimeters to a few centimeters, If two magnets attract each other, the distance will be even greater.

Explanation of the relationship between magnetic attraction distance and magnetic force;

Suction force ≠ distance. An increase in suction does not necessarily mean a proportional increase in adsorption distance;

Magnetic force decreases exponentially with distance, meaning that as the distance doubles, the suction force may decrease to 1/4 or even less of its original value;

To increase the adsorption distance, the magnet needs to be made larger and thicker, and the magnetic grade should also be selected at a higher level, such as N52 or N54.

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