Recent content by downtownjapan

Hi everyone, I am trying to calculate the decrease in magnetic field strength over distance, using a formula I found on this thread https://www.physicsforums.com/showthread.php?t=522223 The formula given was 1/r^3, where r is the distance from the source. The same thread says the formula...

Hi everyone, I am trying to use the 1/r^3 formula to calculate the decrease in magnetic field strength over distance, but I must be doing something very, very wrong following this formula because the numbers I get don't make sense to me. I have clearly made a mistake applying the formula and...

Hi, I am interested in making my own (weak) magnets exposing some ferrous metal to the magnetic field of an electromagnet, but this is theoretical rather than something I am able to actually do right now. I am wondering if there are any formulas that can help calculate/estimate the resulting...

Hi everyone, I have a plastic rod that is cut/snapped between two metal clamps. I want the break in the material to be at an angle perpendicular to the rod's surface. Can anyone tell me what factors effect this operation? How can I select the best material for the plastic rod? Thanks in...

Hi everyone, I am interested in using an electromagnet to repel a permanent magnet and lift it up, and I am thinking about how to go about calculating the required magnetic field strength of the electromagnet for this operation. I have attached a rough conceptual drawing showing the...

Can anyone add any information on calculating how the field changes when the distance is very, very small? For example 0.000075 meters? I am assuming the 1/r^3 formula does not apply at this distance. I have a coil 0.00004 meters in diameter producing a magnetic field of 31.69 tesla. Can...