The distance at which magnet can attract

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SUMMARY

The discussion centers on the distance at which one magnet can attract another, specifically addressing the scenario of two magnets positioned 1 meter apart. It is established that while magnets can attract each other from any distance, the force of attraction diminishes significantly with distance, following the inverse cube law (1/d^3). This means that doubling the distance results in an eightfold decrease in the attractive force. The conversation also highlights misconceptions about the nature of magnetic attraction in popular media, emphasizing that such portrayals often misrepresent scientific principles.

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Is it possible for one magnet to attract another over a distance of 1m? To specify, if magnet 1 was at point A on the East side of the ruler, and magnet 2 was stationary at point B on the West side of the ruler. Could magnet 2 attract magnet 1 so much that both were bound together at point B on the West Side of the Ruler?
 
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Yes, it is.
 
what size of magnet would i need? and would it have to be electromagnetic
 
Sure. In fact, assuming the poles are oriented correctly, the magnets already attract each other from any distance. The force of the attraction falls off at a distance though. If you double the distance the attractive force decreases by 4x. So after a bit the force can no longer overcome friction. This is why magnets don't usually go flying across the room to another one.
 
Drakkith said:
If you double the distance the attractive force decreases by 4x
Ooouch? Are you quite sure that number? Maybe rather 8?
 
xts said:
Ooouch? Are you quite sure that number? Maybe rather 8?

I didn't think so. It falls off with the square root correct? Doubling the distance is 4 times less, quadrupaling the distance would be 16 times less, and etc right?
 
Put a REALLY big magnet at B and a light one at A :smile:
 
Drakkith said:
I didn't think so. It falls off with the square root correct? Doubling the distance is 4 times less, quadrupaling the distance would be 16 times less, and etc right?

So when you have seen in a movie the bad evil guy using his super ultra magneto-gizmo weapon it usually is bad science.
 
It falls off with the square root correct?
Not quite correct. At larger distances (comparing to magnet size) falls with 1/d^3. Doubling the distance makes 8 times smaller force.
Guess why?
 
  • #10
xts said:
Not quite correct. At larger distances (comparing to magnet size) falls with 1/d^3. Doubling the distance makes 8 times smaller force.
Guess why?

Ah ok. I must have been thinking in 2d. :biggrin:

So when you have seen in a movie the bad evil guy using his super ultra magneto-gizmo weapon it usually is bad science.

Usually yes. Although it depends on the circumstances in the film.
 

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