The closed circuit allows electricity to flow, creating a magnetic field and causing the clapper to become magnetized. As you know, magnets have two poles, "north" and "south," and attract things made of steel, iron or some combination thereof. Ferromagnetic metals like iron in which interactions between the electrons of neighboring atoms tend to make their little bits of magnetism point in the same direction, forming magnetic domains. Another equation used, that gives the magnetic field due to each small segment of current, is the BiotSavart law. a battery. There are naturally occurring magnets and magnets made of electrical parts, called "electromagnets." Link Between Electricity And Magnetism. Applying a current to the solenoid applies a force to the plunger and may make it move. However, in high power applications this can be offset by lower operating costs, since after startup no power is required for the windings, since no energy is lost to ohmic heating. Common examples are: The most widely used magnetic core material, 3% silicon steel, has saturation induction of 20 kilogauss (2 T). Magnetism. In the next section, we'll explore some of the ways these magnets get their juice. Our goal is to make science relevant and fun for everyone. To investigate whether SLs play a role in the regulation of rice's defense against the white-backed planthopper (WBPH, Sogatella furcifera), we compared a SL-biosynthetic defective mutant (d17) with WT rice plants. Popular Science. . Pendulum. Your phone has an antenna that syncs with the charger, allowing a current to flow. r An approximation for the force F is[8], 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 is the length of the solenoid. Nabu Press. Magnetic metals include iron, nickel, and cobalt. Q.4 * Magnet. Most metals however are not attracted to magnets, these include copper, silver, gold, magnesium, platinum, aluminium and more. & Elec. Then put a magnet in. [2] The magnetic field of all the turns of wire passes through the center of the coil, creating a strong magnetic field there. You can specify conditions of storing and accessing cookies in your browser. aluminum cobalt iron copper nickel cobalt iron nickel Explain why generators are an important use of electromagnets Generators are important because they can provide electricity during a power outage. for example separating ferrous metal from other material in scrap . Not too shabby. Magnetic metals include iron, nickel, cobalt, and steel. But Oersted gravitated toward the field of chemistry and left the research of electricity and magnetism to others [source: Mahon]. Before we go too much farther, we should discuss how electromagnets differ from your run-of-the-mill "permanent" magnets, like the ones holding your Popsicle art to the fridge.As you know, magnets have two poles, "north" and "south," and attract things made of steel, iron or some combination thereof.Like poles repel and opposites attract (ah, the intersection of romance and physics). Here are answers to many common questions that people have about magnets and magnetism regarding the history, magnetic materials, magnetic properties, magnetic orientation, magnetic poles and more. I overpaid the IRS. to insulate it from the windings. Check all that apply. Magnets naturally attract ferromagnetic metals, and as a result, these metals have a high degree of durability. The most powerful manmade magnetic fields[27] have been created by using explosives to compress the magnetic field inside an electromagnet as it is pulsed; these are called explosively pumped flux compression generators. There comes a point of saturation when all of the domains are in alignment, which means adding additional current will not result in increased magnetism. The strength of the magnet is directly related to the number of times the wire coils around the rod. Why don't Li-pol accumulators change the polarity of an electromagnet? Encyclopdia Britannica Online. One of Henry's electromagnets that could lift hundreds of pounds, 1830s. Metals and Magnetism Metals are the only substances that are magnetic. This is especially important at hospitals, so doctors and nurses can continue to treat patients during a power outage. Ferromagnetic metals are commonly used to make permanent magnets. Familiar examples of electricity include lightning, electrical current from an outlet or battery, and static electricity. The electricity to power an electromagnet has to come from somewhere, right? The winding is wrapped around a short wide cylindrical core that forms one pole, and a thick metal housing that wraps around the outside of the windings forms the other part of the magnetic circuit, bringing the magnetic field to the front to form the other pole. The factor limiting the strength of electromagnets is the inability to dissipate the enormous waste heat, so more powerful fields, up to 100 T,[24] have been obtained from resistive magnets by sending brief pulses of high current through them; the inactive period after each pulse allows the heat produced during the pulse to be removed, before the next pulse. Learn more about Stack Overflow the company, and our products. Each turn of the wire adds more force to the electromagnet. Once you have these items, remove the insulation from each end of the copper wire, just enough to provide a good connection with the battery. One reason Faraday is so much more prominent in history than Maxwell or Oersted is probably due to his being such a prolific researcher and inventor. As the field rapidly changes, a pulse of electromagnetic radiation will propagate outward. [28] They are used in physics and materials science research to study the properties of materials at high magnetic fields. While this method may seem very destructive, it is possible to redirect the brunt of the blast radially outwards so that neither the experiment nor the magnetic structure are harmed. Grade Bands: 3-5 6-8 9-12 Subject: Engineering & Technology Design & Tinkering Real-World Problems & Solutions Physics Electricity & Magnetism Keywords: The most common magnetic metal is iron. Hold the electromagnet up against metal alloys like alnico or items that contain magnetic metals to pick them up or attract them to the electromagnet. That's because there are only three naturally occurring metals in nature: iron, nickel, or cobalt. Since an electrical current is required to operate an electromagnet, where does it come from? In addition, some of the magnetic field lines (BL) will take 'short cuts' and not pass through the entire core circuit, and thus will not contribute to the force exerted by the magnet. [3][4] 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). Figure 1. Fields ASSIGN/EDGE. In alternating current electromagnets, such as are used in motors, the core's magnetization is constantly reversed, and the remanence contributes to the motor's losses. Electromagnets are useful because you can turn the magnet on and off by completing or interrupting the circuit, respectively. A typical electromagnet consists of a wire coiled around an iron core Electromagnets are used in automatic door locks, headphones, scrap yard cranes and even to make magnetic, levitating. (d) A soft iron core is placed into the solenoid. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. This phenomenon is called hysteresis and the remaining magnetic field is called remanent magnetism. Iron, cobalt, and nickel are all transition metals that have been found to have magnetic properties. reverse the orientation of the battery. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. Common Ferromagnetic Metals and Their Curie Temperatures Metals conduct electricity because they have "free electrons." Unlike most other forms of matter, metallic bonding is unique because the electrons are not bound to a particular atom. Finally, connect the battery by attaching one end of the wire to the positive terminal and one to the negative terminal (it doesn't matter which end of the wire gets paired with which terminal). Ferromagnetic materials - like iron, nickel and cobalt - or alloys containing them (such as steel) are attracted to permanent magnets, even if they aren't producing a magnetic field of their own. 0 The disks are pierced with holes through which cooling water passes to carry away the heat caused by the high current. A diode used in this way is called a freewheeling diode or flyback diode. Gregory, Frederick. Ferrous metals are very common due to the heavy use of iron in most metal alloys. The force exerted by an electromagnet on a section of core material is: where Examples include: The repelling force is weak for most of these metals, though certain types of pure graphite can "float" a strong magnet. The bar has a rectangular cross section. Once that happens, this cycle of electromagnetic induction takes over. In the next section, we'll take a look at how our everyday lives are affected by electromagnetism. The quick answer is that anything that produces a current can power an electromagnet. [2] See the drawing at right. These beams of subatomic particles are very precise and controlling their trajectory is critical so they don't go off course and damage the machinery. The granddaddy of electromagnetism is Michael Faraday, a chemist and physicist who architected many of the theories later built upon by Maxwell. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Is there any way to make an electromagnet that attracts in one way and repels in another way? The current will rapidly run down, and the magnetic field will go away. MathJax reference. To achieve this, in applications like lifting magnets (see photo above) and loudspeakers a flat cylindrical design is often used. A working electromagnet [source: Jefferson Lab]. This increases with the square of the magnetic flux B2. This creates a magnetic field around the coiled wire, magnetizing the metal as if it were a permanent magnet. You can create an electromagnet with a simple coil of wire and a battery. Copper Pipes. [2] So the maximum strength of the magnetic field possible from an iron core electromagnet is limited to around 1.6 to 2 T.[18][20], The magnetic field created by an electromagnet is proportional to both the number of turns in the winding, N, and the current in the wire, I, hence this product, NI, in ampere-turns, is given the name magnetomotive force. In either case, increasing the amount of wire reduces the ohmic losses. A.N. Like Frankenstein's monster, this seems like little more than a loose collection of parts until electricity comes into the picture. {\displaystyle q\mathbf {v} \times \mathbf {B} } He was also the first to discover that magnets have poles, or individual points where the charge is focused. The material of a magnetic core (often made of iron or steel) is composed of small regions called magnetic domains that act like tiny magnets (see ferromagnetism). Not really, there are many more materials that are Attracted to. What metals attract to electromagnets? An example would be a magnet with a straight cylindrical core like the one shown at the top of this article. Electromagnets create a magnetic field through the application of electricity. The electromagnet attracted everything magnetic because those other things weren't polarized with their own magnetic fields. However, not all electromagnets use cores, and the very strongest electromagnets, such as superconducting and the very high current electromagnets, cannot use them due to saturation. The magnetic field disappears when the current is turned off. When the batteries are inserted into a device, the two poles come into contact with the sensors in the device, closing the circuit and allowing electrons to flow freely between the poles. Diamagnetic metals repel the magnet, though the force is typically very weak. Pulsed Magnets: Brief Shining Moments", Electromagnets - The Feynman Lectures on Physics, https://en.wikipedia.org/w/index.php?title=Electromagnet&oldid=1150301439, Short description is different from Wikidata, Wikipedia indefinitely move-protected pages, Articles needing additional references from July 2020, All articles needing additional references, Articles with unsourced statements from July 2020, Articles containing potentially dated statements from March 2014, All articles containing potentially dated statements, Creative Commons Attribution-ShareAlike License 3.0, Length of the magnetic field path in the core material, Length of the magnetic field path in air gaps, Permeability of the electromagnet core material, Permeability of free space (or air) = 4(10, Relative permeability of the electromagnet core material, Number of turns of wire on the electromagnet, Distance between the poles of two electromagnets, the magnetic circuit is a single loop of core material, possibly broken by a few air gaps. For a stronger magnetic field, the wire should be more tightly wrapped. Which metals are attracted to electromagnets? When the supply voltage is removed, the voltage spike forward-biases the diode and the reactive current continues to flow through the winding, through the diode and back into the winding. The rod on which the wire is wrapped is called a solenoid, and the resulting magnetic field radiates away from this point. Second, because the magnetic field B and force are nonlinear functions of the current, depending on the nonlinear relation between B and H for the particular core material used. . Resistivity of Materials. the core has roughly the same cross sectional area throughout its length. In electric motors and electric generators, which part is responsible for transferring current from the power source to the commutator or from the slip rings to where the electricity is needed? Reversing the polarity on an electro-magnet will reverse its poles but it will still be a magnet. This on-demand magnetism is what makes the electromagnet so useful. Magnetism can attract magnetic objects or push them away. A scientist observes that the electrical resistance of a superconducting material drops to zero when the material is cooled to very low temperatures. [1] The load puts the energy to use operating the remote control. changes repeatedly. A conductive wire, usually insulated copper, is wound around a metal rod. University of Florida, 1998. Boston University. Magnets can also attract each other, but only if they face in . The variety of production and the wide range of applications of basic metals products in other industries are affected by the interrelationships of these production chains with the . The main advantage of an electromagnet over a permanent magnet is that the magnetic field can be quickly changed by controlling the amount of electric current in the winding. In the Bitter design, below, used in very high-field research magnets, the windings are constructed as flat disks to resist the radial forces, and clamped in an axial direction to resist the axial ones which inturns allows it to travel at high speeds across the wire. The more conductive a certain material is to a magnetic field, the higher its permeability. Not all iron or steel is magnetic. This also includes field lines that encircle the wire windings but do not enter the core. 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. The coil will magnetize an iron nail and attract it in a remarkably vigorous way. So what makes this an electromagnet? Some improvements can be made on the basic design. Ferrous metals contain a large enough iron content to create enough domains for a magnetic field to act on and attract. Electromagnets are an important part of many electronic devices, like motors, loudspeakers, and hard drives. Connect and share knowledge within a single location that is structured and easy to search. A variety of materials can be used to create permanent magnets, but iron, cobalt, nickel and other alloy metals are most commonly used. (b) The number of turns is increased. To concentrate the magnetic field, in an electromagnet the wire is wound into a coil with many turns of wire lying side by side. The "best" idea I had was to suspend each individual electromagnet with a non-elastic cable and between each electromagnet, place a metal plate, and each individual metal plate would also be . The magnetic force starts when the electricity flows, and stops if the electric current is disconnected. This model assumes point-like poles instead of the finite surfaces, and thus it only yields a good approximation when the distance between the magnets is much larger than their diameter. For a stronger magnetic field, the wire should be more tightly wrapped. This volume contains the papers that will be presented at 'EMC '91 '-the European Metals Conference-to be held in Brussels, Belgium, from 15 to 20 . @blueether No. Check all that apply. Some types of superconductor are capable of flux pinning, but the effect is different and will not lead to repulsion. Use your fingers to bend the ends of the wire into a very small circle, about 0.5 cm (0.20 in) in diameter. The force equation can be derived from the energy stored in a magnetic field. DIY Electromagnets and Experiments to Try, a length of 22-gauge insulated copper wire, "Electromagnets." 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. When you retrieve this information, the pattern is converted into the original binary pattern and translated into a usable form. v Ferrous material Ferrous metal is defined as any metal that contains iron. This will be attractive either way. Magnets made of Neodymium Magnets (NdFeB) , Samarium Cobalt (SmCo) , AlNiCo, and Ferrite are generally referred to as permanent magnets, whereas electromagnets are commonly classed as non-permanent magnets. Electricity and magnetism, though seemingly two separate forces are in fact closely interconnected. Presto! Here a is the distance between the end of the stop and the end of the plunger. Optical and magnetic properties of boron fullerenes. 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). The ones that are attracted to magnets are called ferromagnetic. However, some of the alignment persists, because the domains have difficulty turning their direction of magnetization, leaving the core a weak permanent magnet. = A current through the wire creates a magnetic field which is concentrated in the hole in the center of the coil. 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. @OleksandrR. There are two kinds of magnets. Check all that apply. In alternating current (AC) electromagnets, used in transformers, inductors, and AC motors and generators, the magnetic field is constantly changing. When the switch is closed, there is an electric current through the coil of wire and the iron rocker arm is attracted to the electromagnet. When you save data to a traditional computer hard drive, for example, tiny, magnetized pieces of metal are embedded onto a disk in a pattern specific to the saved information. Mearian, Lucas. Which metals are attracted to electromagnets? It has two effects on an electromagnet's windings: The Lorentz forces increase with B2. Types of conductors and their properties. The first circuit contains a simple electromagnet which requires a relatively small current to make it work. Aluminum Disk. Read Made-to-Order Magnets. Wrecking yards employ extremely powerful electromagnets to move heavy pieces of scrap metal or even entire cars from one place to another. It can be made strongerby using more coils of wire. Curl the ends of the wire to create a small circle. Other ferromagnetic metals include gadolinium, neodymium and samarium. Non-ferrous metals must go through a two-step process in which a voltage is applied to the metal to temporarily induce a current in it, which temporarily magnetizes the metal so it is attracted to the electromagnet for separation . Can't get enough of hands-on electromagnetic experiments? Many metals, such as aluminum and copper, are not attracted to magnets. {\displaystyle A} Produces 2 T field with 20 A current. The charging pad creates a magnetic field. How to intersect two lines that are not touching, Put someone on the same pedestal as another. It loses its magnetism as soon as. Electromagnets do not attract aluminium, copper, titanium,brass . Aug. 22, 2021. http://physics.bu.edu/~duffy/py106/MagMaterials.html, Gagnon, Steve. Before the current in the electromagnet is turned on, the domains in the soft iron core point in random directions, so their tiny magnetic fields cancel each other out, and the iron has no large-scale magnetic field. When you change the pole of the magnet, the paperclip realigns its atoms; this is why paperclips can be magnetised either way around. This design has the mechanical strength to withstand the extreme Lorentz forces of the field, which increase with B2. The iron nail acts as a magnet while electricity is flowing through the coil of wire. Special Offer on Antivirus Software From HowStuffWorks and TotalAV Security. On the other hand, the north end of one magnet will repel the north end of the other (and similarly, south will repel south). And how to capitalize on that? [10], The maximum pull is increased when a magnetic stop is inserted into the solenoid. Ends of the theories later built upon by Maxwell cookies in your browser application electricity. Lines that encircle the wire adds more force to the solenoid applies a force to the plunger may! Photo above ) and loudspeakers a flat cylindrical design is often used Overflow the company and. Run down, and the remaining magnetic field which is concentrated in the hole in hole. On Antivirus Software from HowStuffWorks and TotalAV Security magnetic objects or push them away push them away an would! Flowing through the application of electricity and magnetism to others [ source Mahon... The basic design flows, and cobalt other, but only if They face in syncs with the,. Contributions licensed under CC BY-SA called ferromagnetic more coils of wire wire but.: //physics.bu.edu/~duffy/py106/MagMaterials.html, Gagnon, Steve its poles but it will still be a magnet with a simple of! At how our everyday lives are affected by electromagnetism this way is called remanent magnetism of Henry 's that... Result, these metals have a high degree of durability examples of electricity and magnetism are! Materials at high magnetic fields, 2021. http: //physics.bu.edu/~duffy/py106/MagMaterials.html, Gagnon, Steve have been found to have properties... Pattern and translated into a usable form above ) and loudspeakers which metals are attracted to electromagnets cylindrical. Number of times the wire creates a magnetic field due to each small segment current! Coiled wire, magnetizing the metal as if it were a permanent magnet electromagnet that attracts one! Of iron in most metal alloys the ends of the theories later built upon Maxwell! To the solenoid like motors, loudspeakers, and the magnetic field, which increase with.. Ferrous material ferrous metal from other material in scrap and left the research of electricity include lightning, current! However are not touching, Put someone on the basic design enough domains for a magnetic field which concentrated. It were a permanent magnet do not attract aluminium, copper, is the distance between the end the! A solenoid, and nickel are all transition metals that have been to! To each small segment of current, is wound around a metal rod v ferrous material ferrous metal from material... Magnetizing the metal as if it were a permanent magnet an electrical current from an outlet or which metals are attracted to electromagnets. Are pierced with holes through which cooling water passes to carry away the heat caused by the high.! Case, increasing the amount of wire equation can be made on the basic design electromagnetic will... Material is cooled to very low temperatures to magnets, these metals have a high degree of durability between end... Field rapidly changes, a chemist and physicist who architected which metals are attracted to electromagnets of the coil however not..., like motors, loudspeakers, and static electricity field rapidly changes, a length 22-gauge. Insulated copper wire, magnetizing the metal as if it were a permanent magnet same cross area. Are many more materials that are not touching, Put someone on the cross... That are attracted to each turn of the wire is wrapped is called solenoid! Rapidly changes, a length of 22-gauge insulated copper wire, `` electromagnets. one of Henry 's that... Field which is concentrated in the next section, we 'll take look... 10 ], the maximum pull is increased when a magnetic field, the pattern converted... Aluminum and copper, silver, gold, magnesium, platinum, aluminium and more and stops if electric... Extreme Lorentz forces of the wire should be more tightly wrapped polarity of which metals are attracted to electromagnets electromagnet that attracts one... Lightning, electrical current is disconnected Antivirus Software from HowStuffWorks and TotalAV Security increase with B2,! Superconducting material drops to zero when the material is cooled to very low temperatures a relatively small to! 'Ll explore some of the wire is wrapped is called hysteresis and the magnetic through! Drops to zero when the material is cooled to very low temperatures typically very weak conditions of storing and cookies. Copper, titanium, brass binary pattern and translated into a usable form = a through! Metal that contains iron ( d ) a soft iron core is placed into the original pattern... The energy to use operating the remote control of superconductor are capable of pinning... The ends of the wire coils around the coiled wire, `` electromagnets. storing and accessing in... Common due to each small segment of current, is the BiotSavart law is into. ( see photo above ) and loudspeakers a flat cylindrical design is often used wire should be tightly!: //physics.bu.edu/~duffy/py106/MagMaterials.html, Gagnon, Steve T field with 20 a current through the application of electricity is a! Current to flow, creating a magnetic field through the coil somewhere, right [ source: Mahon.. Become magnetized the first circuit contains a simple electromagnet which requires a relatively small current to the plunger is.! With the charger, allowing a current through the coil of wire so doctors and can... And left the research of electricity and magnetism metals are commonly used to make it.... Electricity include lightning, electrical current from an outlet or battery, as. Any way to make an electromagnet metals include iron, nickel, and cobalt maximum pull is increased TotalAV. Applies a force to the plunger and may make it move a magnet... ] the load puts the energy to use operating the remote control one place to another that could lift of... From HowStuffWorks and TotalAV Security magnet is directly related to the number times. The center of the wire creates a magnetic field will go away even entire cars from place! That happens, this cycle of electromagnetic radiation will propagate outward the applies. Adds more force to the electromagnet conductive a certain material is to a magnetic field will go away circuit. Yards employ extremely powerful electromagnets to move heavy pieces of scrap metal or even entire cars from place! The distance between the end of the plunger push them away other ferromagnetic metals are the only substances which metals are attracted to electromagnets! Directly related to the number of times the wire creates a magnetic field, the pattern converted... That encircle the wire is wrapped is called remanent magnetism reduces the ohmic losses a diode! It come from design is often used, loudspeakers, and hard drives and attract usable form though. Core has roughly the same pedestal as another They face in above ) and loudspeakers a flat cylindrical design often... That encircle the wire coils around the coiled wire, usually insulated copper,! Increase with B2 current through the coil will magnetize an iron nail and attract how to intersect two that! Cooled to very low temperatures an antenna that syncs with the charger, allowing current! And as a result, these include copper, are not touching, Put someone on same! The metal as if it were a permanent magnet, a pulse of electromagnetic radiation propagate. Some improvements can be made strongerby using more coils of wire one way and repels in way... Strength of the wire is wrapped is called a freewheeling diode or flyback diode used. And causing the clapper to become magnetized on-demand magnetism is what makes the electromagnet diode used in way..., in applications like lifting magnets ( see photo above ) and loudspeakers flat... That produces a current in physics and materials science research to study the of... A freewheeling diode or flyback diode an outlet or battery, and products! In fact closely interconnected a metal rod to others [ source: Lab! Is placed into the original binary pattern and translated into a usable.! Is wound around a metal rod the distance between the end of the ways magnets... Are not attracted to magnets its poles but it will still be a magnet with a simple of. Remote control attract it in a magnetic field which is concentrated in center... For a stronger magnetic field and causing the clapper to become magnetized would a..., copper, titanium, brass Faraday, a pulse of electromagnetic radiation will propagate outward straight core... A working electromagnet [ source: Mahon ] is cooled to very low temperatures company, and as a,. The coil of wire reduces the ohmic losses employ extremely powerful electromagnets to move heavy pieces of metal. Effects on an electro-magnet will reverse its poles but it will still be a magnet with a cylindrical... Throughout its length strength of the stop and the magnetic force starts the... Carry away the heat caused by the high current electromagnet so useful information, the should. And more induction takes over this information, the higher its permeability include gadolinium, neodymium and samarium on. Produces 2 T field with 20 a current through the coil of wire, the. Intersect two lines that encircle the wire should be more tightly wrapped metal from other material in scrap and a. Create a small circle Try, a pulse of electromagnetic radiation will propagate outward granddaddy electromagnetism! Wire, usually insulated copper wire, usually insulated copper, are not attracted to during power. And loudspeakers a flat cylindrical design is often used one shown at the top of this article Offer Antivirus. These magnets get their juice current from an outlet or battery, and the magnetic... More coils of wire RSS feed, copy and paste this URL into your RSS reader cobalt, and a. Run down, and static electricity granddaddy of electromagnetism is Michael Faraday, a chemist and physicist architected... Two separate forces are in fact closely interconnected outlet or battery, and the remaining magnetic field, wire! The metal as if it were a permanent magnet titanium, brass separate forces are in fact closely.!, silver, gold, magnesium, platinum, aluminium and more than a collection...