Contrasting student and also scientific views

Student day-to-day experiences

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Many young students will certainly have had actually memorable however often confound experiences with magnets and magnetic materials. Magnetic materials are consistently encountered approximately the home, regularly holding little objects ~ above the kitchen refrigerator or keeping cupboards and also fridge doors closed. Many children’s toys employ weak magnets come ‘stick’ materials together (e.g. Wood train carriages) or are provided in basic children’s building toys to enable them to quickly assemble more facility structures there is no the need for confusing adhesives or complicated connections. Toys really rarely manipulate magnetic repulsion.

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Many younger students space yet to kind strong see or in many cases any views at all around how magnets interact with matter or every other. They perform not watch the need to discriminate between magnetic forces and electrostatic forces (or gravity). To them, this often appear to be common experiences the the very same invisible non call force, usually just attraction. Because that example, a balloon ‘rubbed’ through a fabric resulting in its attraction to one more object is typically described incorrectly by young college student (and even some adults) as having actually been ‘magnetised’ in part way.

Students’ confusion around non contact forces is discover in the focus idea Electrostatics – Level 4.

It is well created that enlarge students organize a selection of views around magnetism the vary considerably in their sophistication, varying from magnetic models with surrounding ‘clouds’ of action to ideas about ‘electric rays’ and ‘fields’. However, plenty of younger students simply associate magnetism through a ‘pulling force’.  Understandably your naive model has actually no predictive or explanatory power and they frequently do no perceive the should do an ext than identify and label the attractive or the less constant 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)

Scientific view

We typically encounter magnetic fields in our daily experiences (e.g. The earth magnetic field and magnetic fields produced by electrical current). However, the vast bulk of the magnetic fields about us are merely too weak to cause any kind of observed results or continue to be ‘removed native us’ due to the fact that they room utilised in more facility machines like electrical motors and computer hard drives.

Magnetic attraction and repulsion is one of three fundamental non call forces in nature. The various other two pressures are electrostatic and gravitational (see the focus idea forces without call at level 4, Electrostatics – Level 4 and also Gravity - Level 6).

The vast bulk of magnets us encounter (e.g. Refrigerator magnets, door catches and magnetic toys) are produced from materials which space ferrom​agnetic. These products are based upon mixtures the iron, nickel or cobalt together these space the just three recognized ferromagnetic elements. Stronger industrial magnets have the right to be made with these and also the enhancement of much more expensive rare earth elements.

The atom in ferromagnetic materials are different because they have the right to behave like small magnets. Usually the magnetic field around each atom points in a random direction causing them cancelling each other out (see number 1). But if the bordering magnetic ar 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 material (see figure 2). Lock can likewise remain aligned as soon as the surrounding field is removed producing a irreversible magnet.

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Typical magnets found approximately the residence or offered in guitar ‘pick ups’ or fish tank glass cleaners are constructed with ferromagnetic materials and can produce permanent magnetic fields with intensities as much as 3000 times that of the earth’s magnetic field.Ferromagnetic materials are usually really brittle and will easily chip or fracture if to reduce or enabled to slam together. Castle will additionally lose their permanent magnetic nature if boil strongly. All of these actions cause the individual atom to lose their alignment.The magnetic areas surrounding all magnets are claimed to have actually two poles, referred to as North and also South. These names originate native the monitoring that magnets will align in the direction that the earth weak magnetic field if allowed to swing openly i.e. Direction finding magnetic compasses rely on this rule to operate. The ‘north pole’ that a magnet take away this name due to the fact that it constantly points in the direction of the earth’s north geographical magnetic pole.Similar magnetic poles repel and unlike magnetic poles tempt each other. 

Critical teaching ideas

Magnetic forces are non call forces; they pull or press on objects without emotional them.Magnets are just attracted come a couple of ‘magnetic’ metals and not every matter.Magnets space attracted to and repel other magnets.

At criter up to and including Level 3, that is suitable to encourage students come observe and explore magnetic phenomena v play. Students should be assisted to develop straightforward understandings that the it was observed attraction the magnets to some ‘special’ steels (not every metals) and also their attraction and repulsion to other magnets. Students must be motivated to discriminate in between magnetic forces, electrostatic and also gravitational pressures as being different to each other however examples of pressures that have the right to act without physical call taking location i.e. Instances of non contact forces.

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Explore the relationships in between ideas about magnetism and non call forces in the Concept breakthrough Maps –  Electricity and also Magnetism.

Teaching activities

Provide an open problem to be explored via play or through difficulty solving

Provide students with a range of various materials because that them to investigate which ones have magnetic properties. This materials could 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 iron or steel so students can see that being created of a solid metallic material is a common property.

Provide students with a bag that samples (say 12-15) and have them test the samples v a bar magnet or refrigerator magnet to watch which ones room attracted come the magnet.  Ask castle to type the objects right into two separate groups: those that appear to be attractive to a magnet and also those which carry out not.

Invite the college student to offer suggestions of common features that the objects in the group that were attracted come the magnet. Is it their colour, weight or the problem they are made of that may make the difference? have students suggest and also test their ideas to identify feasible common properties.

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Next, ask college student if every objects made of metallic products are magnetic. Have any kind of students had actually experiences which indicate otherwise? Now provide students through a variety of objects do from various metals and also ask them to sort the objects right into two piles, predicting i m sorry objects will be attractive to a magnet and which will not. Some examples of metals and their sources could be: aluminium cans or foil, brass keys, copper nails or wire, stole screws or nails, zinc flashing or solder, stole bolts or nails, command fishing sinkers and also nickel welding rods.  

After sorting the objects students can then test them to check out if they have correctly suspect which products are magnetic.

The intention here is to encourage students to test various materials and also through investigation recognise that just a few metals have magnetic properties. Critical point to it is in made is the in our everyday experience many metals appear to be magnetic since the most widely used steel is stole containing iron.

Open up discussion via a common experience

Most student are acquainted with magnets ‘attracting’ magnetic materials or gift attracted to some metallic surface such together fridges and white boards, but they are much less acquainted with magnetic forces that repel every other. This is do more challenging for students come explore because they must have actually at least two magnets of equivalent strength and many the the familiar advertising refrigerator magnets used for an easy investigations space weak and also constructed in a means that they have actually no i can identify magnetic poles.

Try to attain a variety of ‘fish tank’ glass cleaning magnets i m sorry are supplied in bag or ‘cow magnets’ easily accessible from some agricultural produce stores. The surface of these magnets space well protected and will mitigate the danger of college student accidentally pinching finger or the magnets shedding fragments if tackled roughly.

Ask the student to investigate what they need to do to do the magnets attract and also repel every other. Have them identify different ends of every magnet with identifying stickers. Just how well have the right to the students suspect what will happen when the magnets are lugged near to every other?

Now encourage students to usage masking ice cream to deal with one magnet onto the roof the a toy car. Use the hand held magnet to press the car along without poignant it or to tempt the auto towards the by transforming its orientation. Deserve to students suspect if the magnet on the vehicle will be attractive or repelled by the method of a brand-new magnet?

The intention right here is because that students come recognise the magnets can repel and also attract every other. At this level that is not thought about important because that students to be able to recall that favor poles repel and also unlike poles attract, however to recognise that magnets deserve to repel and attract there is no making physics contact and also that their orientation is important.

Open conversation via a common experience

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Students have the right to be urged to investigate if magnetic pressures pass through various other non magnetic materials. To capture student interest, location a magnet (such together a fish tank glass clean magnet) top top a class table. Introduce another magnet (the various other glass cleaning magnet) under the table so the two room strongly attracted.  Position the magnet so you deserve to move the magnet under the table with your knee or other hand. The magnet on the table height will follow the motion of the magnet below. This mysterious movement of the magnet ~ above the table will certainly impress students yet eventually lock will find the ‘trick’ the the 2nd magnet under the table.

Have the students certain a magnet to a was standing or the optimal of a tiny water bottle utilizing some ‘blue tack’ or adhesive ice cream so the overhangs the side face of the bottle. Next have them fix a file clip come a length of noodle with sufficient length to with from the table height to the magnet. Ultimately use part ‘blue tack’ to solve the cotton to the table so the file clip is just brief of getting to the magnet and also appears suspended in mid air with a gap between it and the magnet.

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Encourage students to inspection if various products will stop the magnetic force of attraction as soon as they are introduced between the magnet and also the paper clip. Shot sheets the paper, glass, tile, aluminium foil, copper and also zinc sheet. Do any of this materials have an result on to reduce the magnetic force?

The intention below is for students to observe the magnetic pressures will stay unhindered and also can travel with most products without any type of effect.

Helping student workout several of the ‘scientific’ explanations for themselves

Collect a number of uncoated cable coat hangers and also cut and also straighten castle into short lengths which range from 10cm to 20cm long. Distribution a pair of these approximately to students working in pairs or triplets, making certain they space given different sized lengths. Additionally pass approximately a number (5 to 8) of tiny paperclips to every group. Deliberately perform not happen out any type of magnets simply yet to stop students bringing them into call with the wire lengths.

Encourage the students to inspection if any type of of the lengths the wire room successful in attracting any of the paperclips. If the wire lengths have actually not made previous contact with any kind of magnets then they should display no magnetic properties and also not disturb the paperclips.

Now pass out a permanent magnet to every of the college student groups and also demonstrate exactly how you have the right to use one finish of the magnet come stroke the wire length consistently in one direction bring about it to become magnetised. Students deserve to then repeat this through their own lengths that wire and also determine if they have actually been successful in make a magnet by experimentation its ability to lure or background up numerous paperclips. 

This technique of magnetisation is continuous with the idea of making use of a magnetic field (from the magnet) to significantly align the direction that the atoms acting as tiny magnets in the wire. Share this explanation through students is no recommended.

Have students describe what castle did and also discuss how successful they to be in do a magnet.

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Collecting evidence and data for analysis

After student have efficiently made one length of wire right into a irreversible magnet, set them the difficulty of make the most an effective magnet lock can. They can again test their success by attracting and lifting as countless of the paperclips together they can with your wire magnets. Have students indigenous each team record the variety of paperclips your magnet have the right to lift. Encourage students come investigate various properties the the wires that may contribute to making far better magnets e.g. Compare the variety of times each to be stroked, the size of the wires and the methods used come stroke each wire.