{"id":3243,"date":"2018-07-12T09:52:00","date_gmt":"2018-06-28T18:11:24","guid":{"rendered":"http:\/\/commons.princeton.edu\/josephhenry\/eddy-currents\/"},"modified":"2024-08-06T18:14:12","modified_gmt":"2024-08-06T23:14:12","slug":"eddy-currents","status":"publish","type":"page","link":"https:\/\/commons.princeton.edu\/josephhenry\/eddy-currents\/","title":{"rendered":"Eddy Currents"},"content":{"rendered":"

Tesla Pratt, 6\/19\/24 \u2014 Professor Littman<\/span><\/p>\n

An eddy current is a loop of current created within a conductive body by a changing magnetic field \u2013 relative motion between the conductor and magnet. Eddy currents follow Faraday\u2019s Law of Induction, \"\\varepsilon=-N<\/span>\u00a0and are created in planes perpendicular to the direction of the magnetic field.\u00a0<\/span>The strength of an eddy current is directly proportional to the strength of the magnetic field, the area of the conductive surface, and the rate of change of flux.\u00a0<\/span><\/p>\n

Objective:<\/strong> Study the shape and formation of eddy currents within different conducting bodies and relative motion.<\/span><\/p>\n

Senario 1 – Spinning Disc:\u00a0<\/strong><\/p>\n

In the case of a rotating disc, the speed at which the disc rotates determines the rate of change in flux, so angular velocity<\/strong> is directly proportional to the strength of the eddy current. This statement is confirmed by my comsol simulation of different disc speeds \u2013 in the images below, as we decrease speed by factors of ten, the current density (visible in a scale on the right) decreases by the same factor.\u00a0<\/span><\/p>\n

Angular Velocity of Disc \u2013 Effect on Current<\/strong><\/p>\n

100RPM, Scale(A\/m^2): x10^6\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 10RPM, Scale(A\/m^2): x10^5\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a01RPM, Scale(A\/m^2): x10^4<\/p>\n

\"\"\"\"\"\"<\/p>\n

Disc Velocity Increasing from Zero<\/strong><\/p>\n

When the disc is at rest, there is no relative movement between the conductive body, and magnetic field so no eddy currents are present. Right as the disc starts to move eddy currents begin to form in the plate, and continue to increase in strength as the disc picks up speed. This is consistent with our data above.<\/span><\/p>\n