Contrasting student and also scientific views
Student daily experiences
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Many younger students space yet to kind strong see or in many cases any type of views at all about how magnets interact with matter or each other. They carry out not see the should discriminate in between magnetic forces and electrostatic forces (or gravity). To them, these often show up to be typical experiences that the same invisible non contact force, usually only attraction. For example, a balloon ‘rubbed’ v a towel resulting in the attraction to another object is typically described erroneously by young college student (and also some adults) as having actually been ‘magnetised’ in part way.
Students’ confusion about non call forces is discover in the emphasis idea Electrostatics – Level 4.
It is well created that enlarge students hold a selection of views around magnetism the vary significantly in your sophistication, varying from magnetic models with neighboring ‘clouds’ of activity to ideas about ‘electric rays’ and also ‘fields’. However, plenty of younger students simply associate magnetism through a ‘pulling force’. Understandably their naive model has no predictive or explanatory power and they typically do not perceive the must do an ext than identify and also label the attractive or the less frequent repelling behaviour together magnetic.
Research: Erikson (1994), Borges & Gilbert (1998), Haupt (2006), valve Hook & Huziak-Clarke (2007), Ashbrook (2005), Hickey & Schibeci (1999), Maloney, O’Kuma, Heieggelke & van Heuvelen (2001)
We generally encounter magnetic areas in our everyday experiences (e.g. The earth magnetic field and magnetic fields developed by electrical current). However, the vast bulk of the magnetic fields roughly us are simply too weak to cause any kind of observed effects or remain ‘removed indigenous us’ because they are utilised in more complicated machines like electrical motors and also computer tough drives.
Magnetic attraction and repulsion is one of three an essential non contact forces in nature. The other two forces are electrostatic and gravitational (see the emphasis idea forces without call at level 4, Electrostatics – Level 4 and also Gravity - Level 6).
The vast majority of magnets we encounter (e.g. Fridge magnets, door catches and also magnetic toys) are made from materials which room ferromagnetic. These products are based on mixtures of iron, nickel or cobalt together these room the just three well-known ferromagnetic elements. Stronger industrial magnets have the right to be made v these and the addition of more expensive rare earth elements.
The atom in ferromagnetic products are different because they deserve to behave like little magnets. Normally the magnetic field approximately each atom clues in a random direction resulting in them cancelling each other out (see figure 1). But if the surrounding magnetic field is strong enough, it is feasible for them come align for this reason they each add to produce a more powerful magnetic field in the product (see figure 2). Lock can additionally remain aligned as soon as the surrounding ar is removed producing a long-term magnet.
Typical magnets found approximately the residence or offered in guitar ‘pick ups’ or fish tank glass cleaners are built with ferromagnetic materials and can develop permanent magnetic areas with intensities approximately 3000 times that of the earth magnetic field.Ferromagnetic products are usually really brittle and will easily chip or fracture if reduce or enabled to slam together. Lock will also lose their irreversible magnetic properties if boil strongly. Every one of these actions cause the individual atom to shed their alignment.The magnetic fields surrounding every magnets are claimed to have two poles, referred to as North and South. This names originate indigenous the monitoring that magnets will certainly align in the direction the the earth’s weak magnetic field if permitted to swing freely i.e. Direction detect magnetic compasses depend on this rule to operate. The ‘north pole’ that a magnet take away this name because it constantly points towards the earth’s north geographic magnetic pole.Similar magnetic poles repel and unlike magnetic poles attract each other.
Critical to teach ideasMagnetic pressures are non contact forces; they traction or push on objects without touching them.Magnets are only attracted to a few ‘magnetic’ metals and not all matter.Magnets are attracted to and also repel various other magnets.
At standards up to and including Level 3, it is appropriate to encourage students to observe and also explore magnetic phenomena through play. Students must be assisted to develop simple understandings that the it was observed attraction that magnets to some ‘special’ steels (not every metals) and also their attraction and also repulsion to other magnets. Students should be urged to discriminate in between magnetic forces, electrostatic and gravitational forces as being various to each other however examples of forces that deserve to act without physical contact taking location i.e. Examples of non contact forces.
Provide one open difficulty to be discover via beat or through problem solving
Provide students through a variety of various materials because that them to investigate which ones have actually magnetic properties. This materials can include samples of: paper, plastic, polystyrene, wood, glass, rope, leaves, ceramic, rock, and some objects made of steel or steel. Look to use just metallic objects do from stole or steel so students can see that being composed of a solid metallic product is a usual property.
Provide students with a bag that samples (say 12-15) and also have them check the samples through a bar magnet or fridge magnet to watch which ones room attracted to the magnet. Ask them to type the objects into two separate groups: those that show up to be attracted to a magnet and those which perform not.
Invite the college student to market suggestions of typical features that the objects in the team that were attracted to the magnet. Is it their colour, weight or the substance they room made of that may make the difference? have actually students suggest and test their ideas to identify feasible common properties.
After sorting the objects students can then check them to see if they have actually correctly suspect which materials are magnetic.
The intention here is to encourage students come test assorted materials and also through investigation recognise that only a couple of metals have magnetic properties. An important point to it is in made is the in our everyday experience most metals appear to it is in magnetic because the many widely used metal is steel containing iron.
Open up discussion via a common experience
Most student are familiar with magnets ‘attracting’ magnetic products or gift attracted to some metallic surface such as fridges and white boards, yet they are far less acquainted with magnetic forces that repel every other. This is make more challenging for students come explore due to the fact that they must have actually at the very least two magnets of similar strength and also many that the acquainted advertising refrigerator magnets supplied for an easy investigations space weak and also constructed in a method that they have no identifiable magnetic poles.
Try to obtain a number of ‘fish tank’ glass cleaning magnets which are offered in bag or ‘cow magnets’ accessible from some farming produce stores. The surface of these magnets room well protected and will reduce the threat of students accidentally pinching fingers or the magnets shedding fragments if handled roughly.
Ask the students to inspection what they should do to do the magnets attract and repel every other. Have actually them identify various ends of each magnet with identifying stickers. How well can the students predict what will occur when the magnets are brought near to every other?
Now encourage college student to use masking ice to fix one magnet onto the roof the a toy car. Usage the hand held magnet to press the auto along without touching it or to lure the car towards that by changing its orientation. Deserve to students suspect if the magnet ~ above the vehicle will be attracted or repelled through the approach of a new magnet?
The intention here is because that students to recognise the magnets deserve to repel as well as attract every other. At this level that is not thought about important for students to be able to recall that prefer poles repel and unlike poles attract, yet to recognise the magnets can repel and also attract there is no making physical contact and that your orientation is important.
Open conversation via a shared experience
Have the students certain a magnet to a stand or the height of a small water bottle using some ‘blue tack’ or adhesive ice so the overhangs the side face of the bottle. Next have actually them fix a document clip come a size of cotton with enough length to with from the table optimal to the magnet. Ultimately use part ‘blue tack’ to fix the noodle to the table therefore the record clip is just brief of reaching the magnet and appears rely in mid air through a gap between it and also the magnet.
The intention right here is because that students come observe the magnetic pressures will stay unhindered and can travel through most materials without any effect.
Helping student workout several of the ‘scientific’ explanations for themselves
Collect a variety of uncoated wire coat hangers and cut and also straighten castle into short lengths which range from 10cm to 20cm long. Distribute a couple of these approximately to students working in bag or triplets, making certain they space given different sized lengths. Additionally pass around a number (5 come 8) of little paperclips to every group. Deliberately perform not pass out any type of magnets simply yet to prevent students bringing castle into call with the cable lengths.
Encourage the college student to inspection if any kind of of the lengths of wire space successful in attracting any type of of the paperclips. If the cable lengths have not do previous call with any type of magnets climate they should present no magnetic properties and also not disturb the paperclips.
Now pass the end a permanent magnet to every of the student groups and also demonstrate just how you deserve to use one end of the magnet to stroke the wire size consistently in one direction causing it to come to be magnetised. Students deserve to then repeat this with their own lengths of wire and determine if they have been successful in making a magnet by experimentation its capability to lure or background up number of paperclips.
This technique of magnetisation is consistent with the idea of making use of a magnetic field (from the magnet) to progressively align the direction the the atoms acting together tiny magnets in the wire. Share this explanation through students is no recommended.
Have students explain what castle did and discuss just how successful they to be in make a magnet.
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Collecting evidence and data because that analysis
After college student have efficiently made one length of wire into a long-term magnet, set them the an obstacle of make the most powerful magnet they can. They can again test your success by attracting and also lifting as countless of the paperclips together they can with your wire magnets. Have students indigenous each group record the number of paperclips their magnet can lift. Encourage students come investigate various properties that the wires the may contribute to making far better magnets e.g. To compare the variety of times each to be stroked, the size of the wires and also the approaches used to stroke each wire.