An example of hysteresis loop is shown in Figure 1.3 (Figure 1.3, National Programme on Technology Enhanced Learning (NPTEL) 2013). The loop has been drawn by using the data collected by measuring the magnetic flux density of a ferromagnetic material by changing the magnetizing force. The intensity of the magnetizing field depends the amount of current applied. The principle used here is the current carrying coil produces a magnetic field which means the conversion of electric field into the magnetic field. From the hysteresis loop, when the amount of applied current increases causes the simultaneous increase in the strength of the magnetizing force H in the positive side accordingly it induces stronger the magnetic field or the magnetic induction …show more content…
When the magnetizing field increased to zero brings the curve to point "e". It will have almost the same level of residual magnetism which was achieved in another direction. Increasing magnetizing field again in the positive direction will reduces flux density to zero. To our notice, the curve does not return back to the origin of the graph because some amount of magnetic force is retained in the material that can be removed by the further application of magnetic field in a positive direction. Then the curve will take a new path from point "f" back to reach the saturation point where it completes the …show more content…
1. Retentivity - It is defined as the ability of the material to retain a certain amount of residual magnetism when the magnetizing force is removed (the magnitude of flux density at a point b on the hysteresis curve).
2. Coercivity - It is termed as the amount of reverse magnetic field to be applied to a magnetic material to reduce the magnetic flux back to zero (the value of ‘H’ at point ‘c’ on the hysteresis curve).
3. Permeability - A property of a material that describes the ease with which a magnetic flux is established in the component.
4. Reluctance – It is the opposition that a ferromagnetic material shows to the establishment of a magnetic field. Reluctance is analogous to the resistance in an electrical
These include, high strength, low weight, high chemical resistance and high cut resistance. This material does not corrode or rust and is also unaffected when placed in or under water.
This is the transitional state from potentiality of the materials to the actualization of the form as describes in the previous step. This step is described by Aristotle ?Again, the primary source of the change or coming to rest; e.g. the man who gave advice is a cause, the father is cause of the child, and generally what makes of what is made and what causes change of what is changed? (Physics, Book II, Chapter III, 194b 30-33). This is a very important stage as we see that though the changes are taking place by changing the physical looks of the materials the underlying nature of the materials is never changed. Thus the internal motions that nature imbues the materials with is in full effect. The reality is nature will not stops is slow movement to the end of the materials it simply allows the physical changes to
This is known as an electromagnet. The current passing through an electromagnet produces a magnetic field. Therefore, the more turns of the coil you have, the greater the magnetic field. and the stronger the electromagnet. This will mean more paper clips.
During the late 1970's, the world of diagnostic imaging changed drastically due to the introduction of Magnetic Resonance Imaging, also known as MRI. For over 30 years, they have grown to become one of the most significant imaging modalities found in the hospitals and clinics ("EDUCATIONAL OBJECTIVES AND FACULTY INFORMATION"). During its ancient days, these machines were referred to as NMRI machines or, “Nuclear Magnetic Resonance Imaging.” The term “nuclear” comes from the fact that the machine has the capability of imaging an atom's nucleus. Eventually, the term was dropped and replaced with just MRI, because “nuclear” did not sit well with the public view ("EDUCATIONAL OBJECTIVES AND FACULTY INFORMATION"). Many people interpreted the machine to produce an excess amount of radiation in comparison to the traditional X-ray machine. What many of them were unaware of, MRI does not disperse a single ounce of ionizing radiation making it one of the safest diagnostic imaging machine available to this date. MRI machines actually use strong magnetic fields and radio waves to produce high quality images consisting of precise details that cannot be seen on CT (Computed Tomography) or X-ray. The MRI magnet is capable of fabricating large and stable magnetic fields making it the most important and biggest component of MRI. The magnet in an MRI machine is measured on a unit called Tesla. While regular magnets commonly use a unit called gauss (1 Tesla = 10,000 gauss). Compared to Earth's magnetic field (0.5 gauss), the magnet in MRI is about 0.5 to 3.0 tesla range meaning it is immensely strong. The powerful magnetic fields of the machine has the ability to pull on any iron-containing objects and may cause them to abruptly move with great for...
A direct current in a set of windings creates a polar magnetic field. A torque acts on the rotor due to its relation to the external magnetic field. Just as the magnetic field of the rotor becomes fully aligned with the external magnetic field, the direction of the current in the windings on the armature reverses, thereby reversing the polarity of the rotor's electromagnetic field. A torque is once again exerted on the rotor, and it continues spinning.
This is know as resistivity. The factors I can investigate are : Ÿ Temperature Ÿ Length Ÿ Cross-sectional area/width Ÿ Material (resistivity) The factor I shall investigate is the length of a wire. Background Knowledge Resistance is when electrons travelling through the wire are impeded by the atoms within the wire. Since the electrons are charge carriers when they collide with the atoms in the wire less pass through.
A conductive atom’s valance shell is not completely full; electrons will flow from atom to atom because of this. When these electrons move from one atom to another, that is electrical current (a brief description of that is). A magnet can be made from different materials, but a loadstone is the natural form. The most important part of magnetism to make electric motors work is: A magnet has two different ends, or poles, a north and a south pole. These poles behave like electric charges, like poles repel and unlike poles attract although magnets have no effect on still charges.
It states that, the amount by which a material body is deformed is linearly related to the force causing the deformation i.e. stress. Or more clearly stress is directly proportional to the deformation. Those solid obey Hook’s l...
Superconductivity can be destroyed if a sufficiently strong magnetic field is applied. A metal in this state has very unique magnetic properties that are unlike those at normal temperatures. A superconductor is often referred to as the perfect diamagnetic. Diamagnetic, ideally, are a class of materials that do not conserve magnetic flux, but expel it. A superconductor is classified as a perfect diamagnetic because by all measurable standards the magnetic flux within the material is zero.
Before understanding the physics principles, one must understand the physical design that induces them. A magnetic disk is a flat, circular, rigid sheet of aluminum coated with a layer of magnetic material (can be double sided). The material usually is a form of iron oxide with various other elements added. The disk rotates upon a central axis and a movable read/write head writes information along concentric tracks (circular paths traced out by motion of the disk) on it. Multiple disks can be stacked to store more information. Typically (1985) 11 disks with 22 surfaces, of which 20 are used (minus top/bottom), are manipulated to read/write data.
When the object is loaded through spring freely that can be considered as elasticity. The simple elasticity consists of a mass, a mass hanger, a steel spring and a retort stand.
...eatment for pain, but in minor cases it may help some individuals recover faster (NCCIH.NIH). For further uses of magnets in the medical fields the NCCIH is researching the integrations of magnets in new contemporary applications to aid in pain relief.
The phenomenon called electromagnetic induction was first noticed and investigated by Michael Faraday, in 1831. Electromagnetic induction is the production of an electromotive force (emf) in a conductor as a result of a changing magnetic field about the conductor and is a very important concept. Faraday discovered that, whenever the magnetic field about an electromagnet was made to grow and collapse by closing and opening the electric circuit of which it was a part, an electric current could be detected in a separate conductor nearby. Faraday also investigated the possibility that a current could be produced by a magnetic field being placed near a coiled wire. Just placing the magnet near the wire could not produce a current. Faraday discovered that a current could be produced in this situation only if the magnet had some velocity. The magnet could be moved in either a positive or negative direction but had to be in motion to produce any current in the wire. The current in the coil is called an induced current, because the current is brought about (or “induced”) by a changing magnetic field (Cutnell and Johnson 705). The induced current is sustained by an emf. Since a source of emf is always needed to produce a current, the coil itself behaves as if it were a source of emf. The emf is known as an induced emf. Thus, a changing magnetic field induces an emf in the coil, and the emf leads to an induced current (705). He also found that moving a conductor near a stationary permanent magnet caused a current to flow in the wire as long as it was moving as in the magnet and coiled wire set-up.
Numerous factors influence electrical conductivity and resistance, two of them are temperature and length of the wire (these are external factors). Electrical conductivity is defined as the property used to describe how well materials allow electrons to flow, and the degree to which a specific material conducts electricity., Electrical conductivity is calculated as the ratio of the current density in the material to the electric field that causes the flow of current. The SI unit of electrical conductivity is Siemens per meter (S/m). Electrical conductivity is also commonly represented by the Greek letter σ (sigma), but κ (kappa) (especially in electrical engineering) or γ (gamma) are alsowhich are occasionally used. Electrical resistivity quantifies how strongly a specific material opposes the flow of electric current. Electrical resistivity is commonly represented by the Greek letter ρ (rho). The SI unit of electrical resistivity is the ohm⋅metre (Ω⋅m) although other units like ohm⋅centimetre (Ω⋅cm) are also in use.
Toughness is the ability of a metal to mutilate plastically and to absorb energy in the process before it breaks or fracture. Metals can be heat treated to alter the properties of strength, ductility, toughness, hardness or resistance to corrosion. This can be done by using heat treatment processes which include precipitation strengthening, quenching, annealing and tempering. Annealing and tempering are the most prominent methods for treating metals. A material may become more or less brittle, harder or softer, or stronger or weaker, depending on the treatment used.