A stent is a cylindrical tube, often made of metal mesh, that\'s inserted into a

Question

A stent is a cylindrical tube, often made of metal mesh, that's inserted into a blood vessel to overcome a constriction. It's sometimes necessary to heat the stent after insertion to prevent cell growth that could cause the constriction to recur. One method is to place the patient in a changing magnetic field, so that induced currents heat the stent. Consider a stainless-steel stent 12 long by 5.0 diameter, with total resistance 50 . Treating the stent as a wire loop in the optimum orientation, find the rate of change of magnetic field needed for a heating power of 270 . dB/dT=___kT/s

Explanation / Answer

given P=270mW =0.27 W

R=50 mohms =0.05 ohms

P=I^2R

I=sqrt(P/R ) =sqrt(0.27/0.05)

I=2.32 A

r=D/2 =5/2 =2.5mm

Area A=pir^2 =pi*(2.5*10^-3)^2 =1.96*10^-5 m^2

E=A(dB/dt)

IR =A(dB/dt)

dB/dt =IR/A =(2.32*0.05/1.96*10^-5)

dB/dt = 5.91KT/s

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