Examples of permanent magnet in the following topics:
-
- Permanent magnets are objects made from ferromagnetic material that produce a persistent magnetic field.
- A permanent magnet is an object made from a material that is magnetized and creates its own persistent magnetic field .
- The counterexample to a permanent magnet is an electromagnet, which only becomes magnetized when an electric current flows through it.
- The iron becomes a permanent magnet with the poles aligned as shown: its south pole is adjacent to the north pole of the original magnet, and its north pole is adjacent to the south pole of the original magnet.
- An example of a permanent magnet: a "horseshoe magnet" made of alnico, an iron alloy.
-
- There are two type of magnets—ferromagnets that can sustain a permanent magnetic field, and electromagnets produced by the flow of current.
- In common language it is often understood that 'magnet' refers to a permanent magnet, like one that might adorn a family's refrigerator, or function as the needle in a hiker's compass.
- Not only do ferromagnetic materials respond strongly to magnets (the way iron is attracted to magnets), they can also be magnetized themselves—that is, they can be induced to become magnetic or made into permanent magnets.
- This induced magnetization can become permanent if the material is heated and then cooled, or simply tapped in the presence of other magnets.
- Conversely, a permanent magnet can be demagnetized by hard blows or by heating it in the absence of another magnet.
-
- Ferromagnetism is the basic mechanism by which certain materials (such as iron) form permanent magnets, or are attracted to magnets.
- This induced magnetization can be made permanent if the material is heated and then cooled, or simply tapped in the presence of other magnets, as shown in .
- Permanent magnets (materials that can be magnetized by an external magnetic field and remain magnetized after the external field is removed) are ferromagnetic, as are other materials that are noticeably attracted to them.
- A group of materials made from the alloys of the rare earth elements are also used as strong and permanent magnets (a popular one is neodymium).
- Not only do ferromagnetic materials respond strongly to magnets (the way iron is attracted to magnets), they can also be magnetized themselves—that is, they can be induced to be magnetic or made into permanent magnets.
-
- Paramagnetism is the attraction of material while in a magnetic field, and diamagnetism is the repulsion of magnetic fields.
- Paramagnetic materials have a relative magnetic permeability greater or equal to unity (i.e., a positive magnetic susceptibility) and hence are attracted to magnetic fields.
- Constituent atoms or molecules of paramagnetic materials have permanent magnetic moments (dipoles), even in the absence of an applied field.
- Generally, the permanent moment is caused by the spin of unpaired electrons in atomic or molecular electron orbitals.
- Unlike ferromagnets, paramagnets do not retain any magnetization in the absence of an externally applied magnetic field, because thermal motion randomizes the spin orientations responsible for magnetism.
-
- Solenoids are loops of wire around a metallic core, and can be used to create controlled magnetic fields.
- Electromagnetism is the use of electric current to make magnets.
- These temporarily induced magnets are called electromagnets.
- An electromagnet creates magnetism with an electric current.
- An electromagnet induces regions of permanent magnetism on a floppy disk coated with a ferromagnetic material.
-
- The magnetic force on a charged particle q moving in a magnetic field B with a velocity v (at angle θ to B) is $F=qvBsin(\theta )$.
- How does one magnet attracts another?
- Magnetic fields exert forces on moving charges, and so they exert forces on other magnets, all of which have moving charges.
- The magnitude of the magnetic force $F$ on a charge $q$ moving at a speed $v$ in a magnetic field of strength $B$ is given by:
- The strongest permanent magnets have fields near 2 T; superconducting electromagnets may attain 10 T or more.
-
- Examples and Applications - Motion of a Charged Particle in a Magnetic Field
- Recall that the charged particles in a magnetic field will follow a circular or spiral path depending on the alignment of their velocity vector with the magnetic field vector.
- This frequency is given by equality of centripetal force and magnetic Lorentz force.
- A magnetic field parallel to the filament is imposed by a permanent magnet.
- Magnetic lines of force are parallel to the geometric axis of this structure.
-
- Magnetic field lines are useful for visually representing the strength and direction of the magnetic field.
- Since magnetic forces act at a distance, we define a magnetic field to represent magnetic forces.
- If magnetic monopoles existed, then magnetic field lines would begin and end on them.
- (A) The magnetic field of a circular current loop is similar to that of a bar magnet.
- Relate the strength of the magnetic field with the density of the magnetic field lines
-
- When an electrical wire is exposed to a magnet, the current in that wire will experience a force—the result of a magnet field.
- When an electrical wire is exposed to a magnet, the current in that wire will be affected by a magnetic field.
- The expression for magnetic force on current can be found by summing the magnetic force on each of the many individual charges that comprise the current.
- In this instance, θ represents the angle between the magnetic field and the wire (magnetic force is typically calculated as a cross product).
- Express equation used to calculate the magnetic force for an electrical wire exposed to a magnetic field
-
- This changing magnetic flux produces an EMF which then drives a current.
- When a conductor carries a current, a magnetic field surrounding the conductor is produced.
- The resulting magnetic flux is proportional to the current.
- From Eq. 1, the energy stored in the magnetic field created by the solenoid is:
- Energy is "stored" in the magnetic field.