function onPageLoad() { //English Units /* document.AppForm.txtBr.value = 11570; document.AppForm.txtBh.value = 32; document.AppForm.txtZ.value = 0; document.AppForm.txtW.value = 0.06; document.AppForm.txtD.value = 0.075; document.AppForm.txtT.value = 0.060; */ //SI Units /* document.AppForm.txtBr.value = 1.157; document.AppForm.txtBh.value = 255; document.AppForm.txtZ.value = 0; document.AppForm.txtW.value = 0.152; document.AppForm.txtD.value = 0.191; document.AppForm.txtT.value = 0.152; */ calcCommonSetup(); } function doCalc() { var z = parseFloat(document.AppForm.txtZ.value); var w = parseFloat(document.AppForm.txtW.value); var d = parseFloat(document.AppForm.txtD.value); var t = parseFloat(document.AppForm.txtT.value); var br = parseFloat(document.AppForm.txtBr.value); if(document.AppForm.ddlMaterials.selectedIndex == 0) { alert('Please select a material!'); document.AppForm.ddlMaterials.focus(); return false; } if ( isNaN(z) ) { alert('Please enter a Z value!'); document.AppForm.txtZ.focus(); return false; } if ( isNaN(w) ) { alert('Please enter an W value!'); document.AppForm.txtW.focus(); return false; } if ( isNaN(d) ) { alert('Please enter a D value!'); document.AppForm.txtD.focus(); return false; } if ( isNaN(t) ) { alert('Please enter an T value!'); document.AppForm.txtT.focus(); return false; } if ( isNaN(br) ) { alert('Please enter a Br value!'); document.AppForm.intBr.focus(); return false; } //Ensure that all values are in SI z = convertLengthToSI(z); w = convertLengthToSI(w); d = convertLengthToSI(d); t = convertLengthToSI(t); br = convertInductionToSI(br); //The effective length/thickness var te = t * getMaterialK(); //in Tesla var fieldStrength = (br / Math.PI) * (Math.atan((w * d) / (2 * z * Math.sqrt(w*w + d*d + 4*z*z))) - Math.atan((w * d) / (2*(z + te) * Math.sqrt(w*w + d*d + 4 * Math.pow(z + te, 2))))); if(document.AppForm.ddlUnits.value == units.English) fieldStrength = fieldStrength * 10000; //convert to Gauss document.AppForm.txtAnswer.value = roundNum(fieldStrength); return true; }

Field Strength of a Rectangular Magnet

These calculations are appropriate for “straight line” (referring to the Normal, B versus H hysteresis loop) magnetic materials such as sintered and bonded ferrite, fully dense neodymium-iron-boron and sintered samarium cobalt magnets.

Please input all values then click on “Calculate”.

Field Strength of a Rectangular Magnet

SI English

---Please Select--- Ferrite SmCo 1:5 SmCo 2:17 NdFeB
Br: gauss

BH(max): MGOe

in.
in.
in.
in.


ANSWER:

gauss

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