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How to Calculate the Weight an Electromagnet Can Pull

Electromagnets produce magnetic force by running electric current through a wire that wraps around a piece of metal. The power of the magnet increases with increases in the number of turns around the piece of metal as well as increases in the amount of current running through the wire. The electromagnet's pull on an object will also decrease as its distance from the magnetic field increases. If we can measure the dimensions of the electromagnet and know the number of turns the wire makes as well as the amount of current being applied, we can calculate the amount of force the magnet will exert on an object at any given distance.

Things You'll Need

Scientific Calculator

Instructions

Calculating the Force
- 1
  Write out the equation:
  
  Force = ((N x I)^2 x k x A) / (2 x g^2)
  
  Where:
  
  N = the number of turns in the solenoid
  
  I = the current, in amperes (A)
  
  A = the cross-sectional area of the magnet in meters squared
  
  g = the distance, in meters, between the magnet and the piece of metal
  
  k = 4 x 3.14159 x 10^-7
  
  ^ = symbol that means to the power of
- 2
  Determine the dimensions of your magnet and the amount of current you will be running through it. For example, if you have a magnet consisting of 500 turns and a cross-sectional area of 0.3 meters squared operating with 10A of current 1.0 meter from the piece of metal you wish to pull, you will have values of:
  
  N=500
  
  I=10A
  
  A= 0.3 meters squared
  
  g= 1 meter
- 3
  Plug the numbers into the equation to compute the force that will act on the piece of metal. This will give you the equation:
  
  Force = ((500 x 10)^2 x 4 x 3.14159 x 10^-7 x 0.3) / (2 x 1.0^2) = 4.712 Newtons (N) or when converted to pounds = 1.0593 pounds as one Newton is equal to 0.224808943 pounds.
  
  This magnet could therefore lift a 1.0593 pound or smaller piece of iron from a distance of one meter.

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