URL:https://pressbooks.bccampus.ca/collegephysics/wp-content/uploads/sites/29/2016/04/Figure_23_09_01a.jpg
掲載元:https://pressbooks.bccampus.ca/introductorygeneralphysics2phys1207opticsfirst/chapter/22-9-magnetic-fields-produced-by-currents-amperes-law/