Read More
Date: 2-5-2021
1521
Date: 18-5-2021
2153
Date: 9-4-2021
1210
|
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.
|
|
حمية العقل.. نظام صحي لإطالة شباب دماغك
|
|
|
|
|
إيرباص تكشف عن نموذج تجريبي من نصف طائرة ونصف هليكوبتر
|
|
|
|
بمشاركة 60 ألف طالب.. المجمع العلمي يستعدّ لإطلاق مشروع الدورات القرآنية الصيفية
|
|
صدور العدد الـ 33 من مجلة (الاستغراب) المحكمة
|
|
المجمع العلمي ينظّم ورشة تطويرية لأساتذة الدورات القرآنية في كربلاء
|
|
شعبة التوجيه الديني النسوي تختتم دورتها الثانية لتعليم مناسك الحجّ
|