Contrasting student and also scientific views
Student day-to-day experiences
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Many kind of younger students are yet to create strong views or in many kind of situations any type of views at all around exactly how magnets connect via issue or each other. They execute not see the need to discriminate between magnetic forces and also electrostatic forces (or gravity). To them, these regularly appear to be widespread experiences of the very same invisible non call force, typically just attraction. For example, a balloon ‘rubbed’ with a towel resulting in its attractivity to one more object is commonly defined mistakenly by young students (and even some adults) as having been ‘magnetised’ in some way.
Students’ confusion around non contact forces is explored in the emphasis idea Electrostatics – Level 4.
It is well establimelted that older students host a range of views around magnetism that vary substantially in their sophistication, ranging from magnetic models via surrounding ‘clouds’ of action to principles around ‘electrical rays’ and ‘fields’. However before, many kind of younger students simply associate magnetism via a ‘pulling force’. Understandably their naive version has no predictive or explanatory power and they frequently do not perceive the should perform more than determine and also label the attractive or the less constant driving away behaviour as magnetic.
Research: Erikkid (1994), Borges & Gilbert (1998), Haupt (2006), Van Hook & Huziak-Clarke (2007), Ashbrook (2005), Hicvital & Schibeci (1999), Maloney, O’Kuma, Heieggelke & Van Heuvelen (2001)
We typically encounter magnetic areas in our everyday experiences (e.g. the Earth’s magnetic area and magnetic fields developed by electrical current). However, the substantial majority of the magnetic fields roughly us are simply also weak to cause any kind of oboffered results or reprimary ‘removed from us’ bereason they are utilised in more facility machines favor electric electric motors and also computer difficult drives.
Magnetic attractivity and repulsion is among three fundamental non contact forces in nature. The other 2 forces are electrostatic and gravitational (see the focus idea Forces without contact at level 4, Electrostatics – Level 4 and Gravity - Level 6).
The huge majority of magnets we enrespond to (e.g. fridge magnets, door catches and magnetic toys) are made from materials which are ferromagnetic. These materials are based upon mixtures of iron, nickel or cobalt as these are the only 3 known ferromagnetic elements. Stronger commercial magnets deserve to be made through these and the enhancement of even more expensive rare earth facets.
The atoms in ferromagnetic products are different bereason they can behave favor little magnets. Normally the magnetic area about each atom points in a random direction bring about them cancelling each other out (view Figure 1). However if the surrounding magnetic field is solid sufficient, it is feasible for them to align so they each contribute to produce a more powerful magnetic field in the product (view Figure 2). They have the right to likewise remajor aligned as soon as the neighboring area is rerelocated developing a irreversible magnet.
Usual magnets discovered around the home or offered in guitar ‘pick ups’ or fish tank glass cleaners are constructed with ferromagnetic products and also deserve to develop permanent magnetic areas via intensities up to 3000 times that of the Earth’s magnetic field.Ferromagnetic products are normally incredibly brittle and will easily chip or fracture if dropped or allowed to slam together. They will also shed their irreversible magnetic properties if heated strongly. All of these actions reason the individual atoms to lose their alignment.The magnetic areas surrounding all magnets are sassist to have actually two poles, called North and South. These names originate from the monitoring that magnets will certainly align in the direction of the Earth’s weak magnetic field if allowed to swing easily i.e. direction finding magnetic compasses rely on this principle to operate. The ‘north pole’ of a magnet takes this name because it always points towards the Earth’s north geographical magnetic pole.Similar magnetic poles repel and unlike magnetic poles entice each other.
Critical teaching ideasMagnetic forces are non contact forces; they pull or press on objects without emotional them.Magnets are just attracted to a few ‘magnetic’ metals and also not all issue.Magnets are attracted to and also repel other magnets.
At standards approximately and also including Level 3, it is proper to encourage students to observe and discover magnetic sensations with play. Students need to be aided to construct basic understandings of the observed attraction of magnets to some ‘special’ steels (not all metals) and their attraction and also repulsion to other magnets. Students should be encouraged to discriminate in between magnetic pressures, electrostatic and gravitational pressures as being different to each other yet examples of forces that deserve to act without physical contact ensuing i.e. examples of non contact forces.
Provide an open up difficulty to be explored using play or with difficulty solving
Provide students via a range of different products for them to investigate which ones have actually magnetic properties. These products could include samples of: paper, plastic, polystyrene, lumber, glass, rope, leaves, ceramic, rock, and also some objects made of iron or steel. Look to use just metallic objects made from iron or steel so students have the right to view that being written of a solid metallic material is a common residential or commercial property.
Provide students via a bag of samples (say 12-15) and also have them test the samples with a bar magnet or fridge magnet to check out which ones are attracted to the magnet. Ask them to kind the objects right into two sepaprice groups: those that appear to be attracted to a magnet and those which do not.
Invite the students to sell suggestions of prevalent features of the objects in the team that were attracted to the magnet. Is it their colour, weight or the substance they are made of that may make the difference? Have students indicate and test their ideregarding determine feasible prevalent properties.
After sorting the objects students can then test them to watch if they have actually effectively predicted which products are magnetic.
The intention here is to encourage students to test miscellaneous materials and also through investigation recognise that just a couple of steels have actually magnetic properties. An vital allude to be made is that in our daily experience the majority of metals show up to be magnetic because the a lot of commonly used metal is steel containing iron.
Open up conversation by means of a shared experience
Many students are acquainted via magnets ‘attracting’ magnetic products or being attracted to some metallic surfaces such as fridges and also white boards, yet they are far less familiar via magnetic pressures that repel each various other. This is made even more challenging for students to discover because they need to have actually at leastern 2 magnets of similar stamina and many of the familiar declaring fridge magnets used for basic investigations are weak and also built in a means that they have actually no identifiable magnetic poles.
Try to attain a variety of ‘fish tank’ glass cleaning magnets which are supplied in pairs or ‘cow magnets’ obtainable from some farming produce stores. The surdeals with of these magnets are well protected and will minimize the risk of students accidentally pinching fingers or the magnets shedding fragments if tackled roughly.
Ask the students to investigate what they should carry out to make the magnets tempt and repel each other. Have them recognize various ends of each magnet via identifying sticker labels. How well can the students predict what will certainly take place as soon as the magnets are brought near to each other?
Now encourage students to usage masking tape to fix one magnet onto the roof of a toy vehicle. Use the hand organized magnet to press the auto alengthy without touching it or to entice the car in the direction of it by transforming its orientation. Can students predict if the magnet on the automobile will certainly be attracted or repelled by the approach of a new magnet?
The intention right here is for students to recognise that magnets can repel and attract each other. At this level it is not considered essential for students to be able to recontact that choose poles repel and also unfavor poles attract, yet to recognise that magnets deserve to repel and tempt without making physical contact and that their orientation is crucial.
Open discussion by means of a common experience
Have the students secure a magnet to a stand also or the top of a small water bottle making use of some ‘blue tack’ or adhesive tape so it overhangs the side confront of the bottle. Next off have them resolve a file clip to a size of cotton with sufficient length to reach from the table optimal to the magnet. Finally usage some ‘blue tack’ to deal with the cotton to the table so the paper clip is just brief of reaching the magnet and also appears suspfinished in mid air through a gap between it and the magnet.
The intention here is for students to observe that magnetic forces will remain unhindered and deserve to take a trip via most products without any effect.
Helping students workout some of the ‘scientific’ explacountries for themselves
Collect a variety of uncoated wire coat hangers and reduced and straighten them into short lengths which array from 10cm to 20cm long. Distribute a pair of these about to students functioning in pairs or triplets, making sure they are provided various sized lengths. Also pass around a number (5 to 8) of little paperclips to each group. Deliberately carry out not pass out any kind of magnets just yet to prevent students bringing them right into contact via the wire lengths.
Encourage the students to investigate if any type of of the lengths of wire are effective in attracting any of the paperclips. If the wire lengths have not made previous call via any kind of magnets then they need to present no magnetic properties and not disturb the paperclips.
Now pass out a long-term magnet to each of the student teams and demonstrate just how you can usage one finish of the magnet to stroke the wire length continuously in one direction causing it to become magnetised. Students have the right to then repeat this with their very own lengths of wire and also identify if they have prospered in making a magnet by experimentation its capability to attract or lift up several paperclips.
This strategy of magnetisation is continual through the concept of making use of a magnetic area (from the magnet) to progressively align the direction of the atoms acting as tiny magnets in the wire. Sharing this explanation via students is not recommfinished.
Have students explain what they did and comment on just how successful they were in making a magnet.
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Collecting evidence and data for analysis
After students have actually efficiently made one size of wire right into a irreversible magnet, collection them the challenge of making the most effective magnet they deserve to. They have the right to aobtain test their success by attracting and lifting as many kind of of the paperclips as they have the right to through their wire magnets. Have students from each group record the number of paperclips their magnet can lift. Encourage students to investigate different properties of the wires that may contribute to making much better magnets e.g. compare the variety of times each was stroked, the size of the wires and also the methods provided to stroke each wire.