MAGNETISM MATTER Magnetic Poles and Bar Magnets
Greetings! I am your educator- Udit Gupta Today, I will guide you regarding the first topic in this chapter which is magnetic poles and bar magnets. https://unacademy.com/user/udit13
Introduction We have seen in the previous courses that a small current loop carrying a current i, produces a magnetic field: Ho 2,0 at an axial point. Here -iA is the magnetic dipole moment of the current loop. The vector A represents the area vector of the current loop current loop placed in a magnetic field B experiences a torque, Also, a
Introduction We also know that an electric dipole produces an electric field 1 2p 4TEo d at axial point and it experiences a torque when placed in an electric field. The two equations for fields and torque are similar in structure. This similarity suggests that the behavior of a current loop can be described by the following hypofhefical model.
Hypothetical Model a) There are two types of magnetic charges, a positive magnetic charge and a negative magnetic charge. A magnetic charge m placed in a magnetic field B experiences a force F = mB The force on a positive magnetic charge is along the field and the force on a negative charge is opposite to the field.
Hypothetical Model b) A magnetic charge m produces a magnetic field at a distance r from it. The field is radially outward if the magnetic charge is positive and is inward if it is negative. c) A magnetic dipole is formed when a negative magnetic charge - m and a positive magnetic charge +m are placed at a small separation d. The magnetic dipole moment is = md and its direction is from-m to +m. The line joining-m and +m is called the axis of the dipole.
Hypothetical Model d) A current loop of area A carrying a current i maybe replaced by a magnetic dipole of dipole moment = md = iA placed along the axis of the loop. The area-vector A points in the direction - m to +m -m +m
Conclusion The model is very useful in studying the magnetic effects and is widely used. It is customary to call a positive charge-North Pole and ar negative magnetic charge - South Pole. They are represented by N and S respectively. From the equation md-IA or F#m8, we can easily see that the unit of pole strength is A-m We can find the magnetic field due to a magnetic dipole at any point P using the equation, for both poles: . Hom
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A Mechanical Engineer from NIT Allahabad here to help learners with physics. Also a Star ⭐ educator.