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Magnetic poles are the ends of a magnet. The exterior field is powerful. Also, the two sides of magnetite are the north and south pole. It refers to magnetic monopoles. The magnetite's south side draws the north side. It is the property of the attraction mechanism behind this. Moreover, the same side of the magnets lead them apart from each other. It refers to a property of repulsion.
Read Also: Magnetism and Matter
| Table of Content |
Key Takeaways: Magnetic field lines, Magnetic poles, Poles of earth, Magnetic field of bar magnet, Bar magnet, Magnetite, Solenoid, magnetic compass, Navigation
What is Magnet?
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An object that generates a magnetic field is known as a magnet. Several things like iron, nickel, cobalt, and steel are attracted by magnetite. A bar magnet is one example. The North and South poles are two different sides of a solenoid. In the early days, a magnetic compass needle helped the sailors with navigation.
Bar Magnet and Fields
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|---|---|---|
| Magnetism and Gauss’s Law | Magnetic Properties of Materials | Magnetisation and Magnetic Intensity |
Magnetic Field Lines
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It consists of magnetic forces that influence a region. The direction of this force is detected by arrows on the line. That is, from the north pole to the south pole of a magnet. The object that has either a north or south pole is monopoles. Moreover, the magnetic field line plot in several ways. For example, place a magnetic field compass in a different direction and look at its movement. This diagram shows the subject to a magnetic field in space at various positions. The image(Figure 1) shows the path of lines and poles in a magnet.
Figure 1. Magnetic field lines
Properties of Magnetic Field Lines
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*The field lines form an endless closed loop. It stretches from the north to the south poles. An electric dipole is not the same as this.
* All the lines contain the same strength.
* When the magnitude of the field is solid, several lines are crossing per unit area.
* Intersection is not seen in magnetic field lines. Also, the direction is not unique at the time of intersecting.
Crucial Formulas of Magnetism.
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Formulas are the basics of every finding. An error brings big trouble for solving questions. So, a correct understanding of formulas gives results fast. Given below are the basic formulas in magnetism.
- Bar magnet as Equivalent Solenoid
Consider the magnetic field of a magnet with radius a, carry a current I, at a distance r on-axis. Hence, the formula is,
\(B = \frac{\mu_0}{4 \pi} \frac{2m}{r^3}\)
Where m is considered as the magnetic moment of a solenoid. Thus, it depicts as,
\(m = \frac{n(2l)}{\pi a^2}\)
- Dipole in Uniform Magnetic field
Take the dipole moment as m places in a magnetic field B with a moment of inertia.
* Magnetic needle act with torque in a uniform magnetic field:
τ = mB sinθ (τ – restoring torque)
* Consider magnetic potential energy as Um.
U m= −m.B
* Work done in a magnetic field by rotating dipole from θ1 to θ2,
W= MB (cos θ1 – cos θ2)
- Electrostatic Analog
Magnetism and current are related to each other. The electric current produces magnetic fields. Hence, the table shows an analogy between magnetic and electric dipoles.
| Description | Electrostatics | Magnetism |
|---|---|---|
| Dipole moment | p | m |
| Equatorial field for a short dipole | \(\frac{-p}{4 \pi \epsilon_0 r^3}\) | \(\frac{-\mu_0 m}{4 \pi r^3}\) |
| Axial Field for a short dipole | \(\frac{2p}{4\pi \epsilon_0 r^3}\) | \(\frac{\mu_0 2m}{4 \pi r^3}\) |
| External Field: torque | p × E | m × B |
| External Field: Energy | –p.E | –m.B |
Things to Remember
- Magnetic poles are the ends of a magnet. The exterior field is powerful. Also, the two sides of magnetite are the north and south pole.
- It is the property of the attraction mechanism behind this. Moreover, the same side of the magnets lead them apart from each other. It refers to a property of repulsion.
- An object that generates a magnetic field is known as a magnet. Several things like iron, nickel, cobalt, and steel are attracted by magnetite. A bar magnet is one example.
- Magnets consist of magnetic forces that influence a region. The direction of this force is detected from the north pole to the south pole of a magnet.
- All the lines contain the same strength. When the magnitude of the field is solid, several lines are crossing per unit area.
Also Read:
| Chapter Related Articles | ||
|---|---|---|
| Permanent and Electromagnets | Earth’s Magnetism | Paramagnetism |
| Ferromagnetism | Magnetic Susceptibility | Curie Weiss Law |
| Current Coil | Magnetic Declination | Curie Constant |
Sample Questions
Ques. How to determine the poles of a magnet? (1 mark)
Ans. The direction of a magnetic field depicts the north and south poles of a magnet. A magnet consists of two sides. The north and south poles are places here.
Ques. What characteristics do magnetic field lines have? (2 marks)
Ans. * When the magnitude of the field is solid, several lines are crossing per unit area.
* Intersection is not seen in magnetic field lines. Also, the direction is not unique at the time of intersecting.
* The field lines form an endless closed loop. It stretches from the north to the south poles. An electric dipole is not the same as this.
* All the lines contain the same strength.
Ques. Define a Magnetic Pole. (1 mark)
Ans. Magnetic poles are the ends of a magnet. The exterior field is powerful. Also, the two sides of magnetite are the north and south pole. It refers to magnetic monopoles.
Ques. Does the earth's magnetic field change with time? (1 mark)
Ans. Yes, It changes with time. Moreover, many years take place to change a particular amount.
Ques. How to plot magnetic field lines? (1 mark)
Ans. The magnetic field line plot in several ways. For example, place a magnetic field compass in a different direction and look at its movement.
Ques. Define a magnet. (1 mark)
Ans. A magnet is an object that produces a magnetic field. Several items like iron, nickel, cobalt, and steel are attracted by magnetite. The different sides of a magnet are north and south poles.
Ques. What is a magnetic monopole? (1 mark)
Ans. The two sides of magnetite are the north and south poles. It refers to magnetic monopoles.
Ques. Is there any difference between magnetic field and flux? (1 mark)
Ans. The area around the magnet in which the charge produces is a magnetic field. Magnetic flux ensures the strength of magnetic lines. The unit of a magnetic field is Tesla, and the magnetic flux is Weber.
Ques. When a compass allows moving in a vertical plane and is placed directly on the geomagnetic north or south pole, which direction does it point? (1 mark)
Ans. At the geomagnetic poles, the earth's magnetic field is perfectly vertical (north and south). In the horizontal plane, the compass needle can freely rotate. As a result, it can point in any direction.
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