Formula for magnetic field strength H = amp x turns / length is well known, but it leads to misleading results. Not to calculate manually we can use this online calculator https://www.omnicalculator.com/physics/solenoid-magnetic-field
First of all this formula does not take into account the diameter of the coil. It is not the same if coil has 1cm radius or 10cm, of course, bigger the radius less flux density for same field strength.
Second and key point is that as we decrease the length of the coil field is supposedly getting proportionally stronger. For example, if we enter just 1 turn, current of 1mA but we decrease the thickness down to 1 millionth of a cm, that is, 0,0000001 cm, we supposedly get a field of ~1,25T.
Now, we sure don't expect that such miscroscopic coil would extend it's field anywhere outside it's microscopic dimensions. It might be 1.25T but only on the microsopic level which is not implicated by this formula.
I am asking cause i am trying to make a strong field inside a 4cm diameter air core coil. But with this formula as only reference i can't be sure of best combination.
For example if i take 1mm thick wire and wind 50 turns of it all in one level and push 20A into it, according to the formula, field strength in the center of the coil will be ~1.3T.
am highly skeptical that this is realistic, again maybe it is on a minute scale, let's say if coil radius is very small..
I am considering taking a thicker wire, more turns, which, ironically, according to the formula does not make field any stronger, but weaker.
Would appreaciate anyone who can clear this up.
First of all this formula does not take into account the diameter of the coil. It is not the same if coil has 1cm radius or 10cm, of course, bigger the radius less flux density for same field strength.
Second and key point is that as we decrease the length of the coil field is supposedly getting proportionally stronger. For example, if we enter just 1 turn, current of 1mA but we decrease the thickness down to 1 millionth of a cm, that is, 0,0000001 cm, we supposedly get a field of ~1,25T.
Now, we sure don't expect that such miscroscopic coil would extend it's field anywhere outside it's microscopic dimensions. It might be 1.25T but only on the microsopic level which is not implicated by this formula.
I am asking cause i am trying to make a strong field inside a 4cm diameter air core coil. But with this formula as only reference i can't be sure of best combination.
For example if i take 1mm thick wire and wind 50 turns of it all in one level and push 20A into it, according to the formula, field strength in the center of the coil will be ~1.3T.
am highly skeptical that this is realistic, again maybe it is on a minute scale, let's say if coil radius is very small..
I am considering taking a thicker wire, more turns, which, ironically, according to the formula does not make field any stronger, but weaker.
Would appreaciate anyone who can clear this up.
