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His first electromagnet was a horseshoe-shaped piece of iron that was wrapped with about 18 turns of bare copper wire ( insulated wire didn't then exist). The iron was varnished to insulate it from the windings. When a current was passed through the coil, the iron became magnetized and attracted other pieces of iron; when the current was stopped, it lost magnetization. Sturgeon displayed its power by showing that although it only weighed seven ounces (roughly 200 grams), it could lift nine pounds (roughly 4 kilos) when the current of a single-cell power supply was applied. However, Sturgeon's magnets were weak because the uninsulated wire he used could only be wrapped in a single spaced out layer around the core, limiting the number of turns. The maximum pull is increased when a magnetic stop is inserted into the solenoid. The stop becomes a magnet that will attract the plunger; it adds little to the solenoid pull when the plunger is far away but dramatically increases the pull when they are close. An approximation for the pull P is [11] P = A N I [ N I ℓ a 2 C 1 2 + C ℓ ] = A N 2 I 2 ℓ a 2 C 1 2 + C A N I ℓ {\displaystyle P=ANI\left[{\frac {NI}{\ell _{\mathrm {a} } http://www.researchgate.net/publication/224606165_High-speed_axial-flux_permanent-magnet_generator_with_coreless_stator
Magnet you use to enlarge - Dan Word
A portative electromagnet is one designed to just hold material in place; an example is a lifting magnet. A tractive electromagnet applies a force and moves something. [8] Some alternator or motor makers utilise aluminum wire (with higher resistance per area than copper (and lower mass)) due to absolute lower overall costs even after the increase in size for a given performance is takem into account. A common tractive electromagnet is a uniformly-wound solenoid and plunger. The solenoid is a coil of wire, and the plunger is made of a material such as soft iron. Applying a current to the solenoid applies a force to the plunger and may make it move. The plunger stops moving when the forces upon it are balanced. For example, the forces are balanced when the plunger is centered in the solenoid. The magnetic domain theory of how ferromagnetic cores work was first proposed in 1906 by French physicist Pierre-Ernest Weiss, and the detailed modern quantum mechanical theory of ferromagnetism was worked out in the 1920s by Werner Heisenberg, Lev Landau, Felix Bloch and others.Magnetic separation equipment, used for separating magnetic from nonmagnetic material, for example separating ferrous metal from other material in scrap. An iron core. Wrap your wire around a piece of iron. Not all iron is equally susceptible to magnetic fields, so experimenting will definitely help here. The ideal iron would be the kind they use in transformers, but that's typically annular which is not ideal for producing exterior magnetic fields. Discussion is with respect to a radial flux machine just so terms match but this applies just as well to axial flux with due change to words used. The maximum uniform pull happens when one end of the plunger is at the middle of the solenoid. An approximation for the force F is [8] F = C A N I / ℓ {\displaystyle F=CANI/\ell }
to enlarge or align a hole in metal How to enlarge or align a hole in metal
There are three main ways to improve your electromagnet without needing a physics degree to model the magnet. Danish scientist Hans Christian Ørsted discovered in 1820 that electric currents create magnetic fields. In the same year, the French scientist André-Marie Ampère showed that iron can be magnetized by inserting it in an electrically fed solenoid. British scientist William Sturgeon invented the electromagnet in 1824. Note that in real-world applications this is not always the case. Economics often matters more than sheer performance per size. Washing machine makers who implement direct drum drive brushless DC motors (with the Fisher & Paykel (now Haier) smartdrive as a superb example) often choose to use ferrite magnets with a consequent larger coil size and so larger diamter rotor and overall machine dimensions as a consequence.Coils are made of conductors with finite resistance (based on material resistivity). This influences the ability to fit a given number of turns within available or desired area and volume. If you have almost zero resistance nonexisteum 45 gauge wire then you can get many turns really close to the magnet surface. Nonexisteum being in vanishingly short supply,manufacturers have turned to cryogenically cooled superconductors to achieve the same effect. Despite the immense cost of providing low cryogenic temperatures and maintaining them continually (eg the electromagnet in an MRI machine is always maintained at cryogenic temperatures and is always "turned on") this is economic compared to classic alternatives, or is the only option when extremely high field strengths over extended areas or volumes are required. Beginning in 1830, US scientist Joseph Henry systematically improved and popularised the electromagnet. [5] [6] By using wire insulated by silk thread, and inspired by Schweigger's use of multiple turns of wire to make a galvanometer, [7] he was able to wind multiple layers of wire on cores, creating powerful magnets with thousands of turns of wire, including one that could support 2,063lb (936kg). The first major use for electromagnets was in telegraph sounders. DSc thesis - DESIGN OF AXIAL-FLUX PERMANENT-MAGNET LOW-SPEED MACHINES AND PERFORMANCE COMPARISON BETWEEN RADIAL-FLUX AND AXIAL-FLUX MACHINES Please forgive me, I am new to this forum and I am not a physics guy but any help would be appreciated. I would like to know how to I increase the range or reach of my electromagnet. By range, I mean the distance from my magnet to a metal object (paper Clip). Currently, my electromagnet has to touch the paper clips to affect them, but I what it to be able to attract them by just coming close with out having to touch. What materials and techniques would be best to achieve this? Thanks for reading where C is a proportionality constant, A is the cross-sectional area of the plunger, N is the number of turns in the solenoid, I is the current through the solenoid wire, and ℓ is the length of the solenoid. For units using inches, pounds force, and amperes with long, slender, solenoids, the value of C is around 0.009 to 0.010psi (maximum pull pounds per square inch of plunger cross-sectional area). [9] For example, a 12-inch long coil ( ℓ = 12 in) with a long plunger of 1-square inch cross section ( A = 1 in 2) and 11,200 ampere-turns ( N I = 11,200 Aturn) had a maximum pull of 8.75 pounds (corresponding to C = 0.0094 psi). [10]
magnetic fields? (article) | Khan Academy What are magnetic fields? (article) | Khan Academy
If it is only the CHANGE IN magnetic flux that is taken into account, why would it make a difference if I was using a 2x1x1/2 magnet or a 2x1/2x1/2?
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