Magnetic polarity

A magnetic field has a direction at any given point in space near a current-carrying wire or a permanent magnet. The flux lines run parallel with the direction of the field. A magnetic field is considered to begin at the north magnetic pole, and to terminate at the south magnetic pole. In the case of a permanent magnet, it is obvious where these poles are.

With a current-carrying wire, the magnetic field just goes around and around endlessly, like a dog chasing its own tail.
A charged electric particle, such as a proton, hovering in space, is a monopole, and the electric flux lines around it aren’t closed (Fig. 1). A positive charge does not have to be mated with a negative charge. The electric flux lines around any stationary, charged particle run outward in all directions for a theoretically infinite distance.

Fig. 1: Electric flux lines around a monopole charge.

But a magnetic field is different. All magnetic flux lines are closed loops. With permanent magnets, there is always a starting point (the north pole) and an ending point (the south pole). Around the current-carrying wire, the loops are circles. This can be plainly seen in the experiments with iron filings on paper. Never do magnetic flux lines run off into infinity. Never is a magnetic pole found without an accompanying, opposite pole.

مواضيع ذات صلة

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التكامل بين تكنولوجيا النانو وتكنولوجيا الاستشعار من بعد لرصد تلوث الهواء الجوي

الحساسات النانوية للحالة الصلبة

الحساسات النانوية لرصد ملوثات الهواء

تكنولوجيا النانو وصناعة الحساسات

الحساسات النانوية

تقنية النانو في الطباعة على الأسطح Nano–Lithography

تقنية الطباعة على الأسطح Lithography

التنافس العالمي في إنتاج الحاسبات المعتمدة على تكنولوجيا النانو

قانون مور

تركيب الترانزستور وكيفية عمله

ماهية الترانزستورات