【導(dǎo)讀】dBthemagicfield. anglebetweends&r. dBperpendiculartor. |dB|proportionalto|ds|. |dB|proportionaltosin?anglebetweends&r. rdsB??Id. 0?rdsB?Id. Where?B=dB1+dB2+…+dBi. .B=SdB. 0?rdsB?Id. 0?Wecanuse. 0?rdsB?Id. 0?rdsB?Id. IdldB?4?×10-7(). Bd?relId??遵循右手定則。r?lId?Bd?r?lId?permeabi