B.Method of Images Approach with Lorentz Force Depth D Image current i R ● 个 o 7777777777777777777777777777 777777777777777∞ 2-R2 x image current-i f iD oi） =2D-2D 2π(2a) 4πa 4π√g2-R2 C.Demonstration:Steady State Magnetic Leviation Figure 11.7.5 When the pancake coil is driven by an ac current,it floats above the aluminum plate.In this experiment,the coil consists of 250 turns of No.10 aluminum wire with an outer radius of 16 cm and an inner one of 2.5 cm.The aluminum sheet has a thickness of 1.3 cm.With a 60 Hz current i of about 20 amp rms.the height above the plate is 2 cm. Courtesy of Hermann A.Haus and James R.Melcher.Used with permission. 6.641,Electromagnetic Fields,Forces,and Motion Lecture 13 Prof.Markus Zahn Page 4 of 146.641, Electromagnetic Fields, Forces, and Motion Lecture 13 Prof. Markus Zahn Page 4 of 14 B. Method of Images Approach with Lorentz Force ( ) 2 2 00 0 2 2 i iD iD f = iD = = 2 2a 4 a 4 R ξ ⎛ ⎞ µµ µ ⎜ ⎟ ⎝ ⎠ π π πξ− C. Demonstration: Steady State Magnetic Leviation Courtesy of Hermann A. Haus and James R. Melcher. Used with permission