Question

Why is the bottom 2r and not 2πr? Can you use Ampere's Law to solve this?

A piece of wire is bent to form a circle with radius r. It has a steady current I flowing through it in a counterclockwise direction as seen from the top (looking in the negative z direction) (Figure 1) Part A What is B2(0), the z component of B at the center (.e., x =y=z=0) of the loop? Express your answer in terms of I, r, and constants like Mo and . Figure (< 1 of 1 > View Available Hint(s) B:(0) = lever Submit Previous Answers ✓ Correct < Return to Assignment Provide Feedback

Answer 1

Sel det ue haue a circular l0op of radiusrdas staady Curunt I flouiuhg through tin a counterclockuwisa dixection Sance ue know Biot-Savart law d 6= uo i dix? 41T 2 dB- Juo I dl&in 411 Since 8-900 foy all taints along the path an d distance to fiesd Paint is costant Then uehaue 2 IT 41m2 =Mo I maghetic tiead at center is- uo i hy tbottom 27 and hat 2mT? You haue used Amkaras law in wTOng way Ampeal law states that,' The lane integral o gultant magnahic a clo&ed curue is sqyual to do anclaed choose path for integrathon,e ema mber that paint at wtich tield in to be daterminad must ie on te bath amd path must haue enough ymmetry o thatintegral can be valy a ted Your chosan path for integpation, does nat haue Yhmetry around circular loop Why io-Savart law jued, hat Ampeslau? field alomg hould When Because tae i ho Such a path that thaut cur paint maghahc ield with Symnatry oround the circular loop