Contrasting student and also scientific views
Student daily experiences
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Many younger students are yet to type strong views or in plenty of cases any views in ~ all about how magnets connect with matter or each other. They do not view the have to discriminate in between magnetic forces and also electrostatic pressures (or gravity). To them, these often appear to be typical experiences that the same invisible non call force, usually just attraction. Because that example, a balloon ‘rubbed’ with a cloth resulting in its 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 approximately non contact forces is discover in the emphasis idea Electrostatics – Level 4.
It is well developed that older students host a range of views about magnetism the vary considerably in their sophistication, ranging from magnetic models with surrounding ‘clouds’ of activity to ideas about ‘electric rays’ and ‘fields’. However, plenty of younger students merely associate magnetism through a ‘pulling force’. Understandably your naive model has no predictive or explanatory power and they commonly do not perceive the must do more than identify and label the attractive or the less regular repelling behaviour as 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 fields in our day-to-day experiences (e.g. The earth magnetic field and magnetic fields created by electric current). However, the vast majority of the magnetic fields about us are just too weak come cause any observed impacts or remain ‘removed native us’ because they space utilised in more facility machines like electric motors and also computer difficult drives.
Magnetic attraction and repulsion is one of three fundamental non call forces in nature. The various other two forces are electrostatic and gravitational (see the focus idea forces without contact at level 4, Electrostatics – Level 4 and also Gravity - Level 6).
The vast majority of magnets we encounter (e.g. Refrigerator magnets, door catches and magnetic toys) are produced from materials which space ferromagnetic. These materials are based upon mixtures the iron, nickel or cobalt together these are the just three well-known ferromagnetic elements. Stronger industrial magnets can be made v these and also the enhancement of much more expensive rare earth elements.
The atom in ferromagnetic materials are different due to the fact that they have the right to behave like little magnets. Typically the magnetic field around each atom points in a random direction bring about them cancelling each various other out (see figure 1). Yet if the bordering magnetic field is strong enough, it is possible for them to align so they each add to produce a stronger magnetic ar in the material (see figure 2). Lock can likewise remain aligned as soon as the surrounding ar is removed producing a permanent magnet.
Typical magnets found roughly the house or provided in guitar ‘pick ups’ or fish tank glass cleaners are constructed with ferromagnetic materials and also can develop permanent magnetic areas with intensities approximately 3000 times the of the earth’s magnetic field.Ferromagnetic products are usually very brittle and also will quickly chip or fracture if to reduce or permitted to slam together. Castle will additionally lose their irreversible magnetic properties if boil strongly. Every one of these actions cause the individual atoms to lose their alignment.The magnetic fields surrounding all magnets are stated to have actually two poles, referred to as North and also South. This names originate indigenous the monitoring that magnets will align in the direction of the earth weak magnetic field if permitted to swing easily i.e. Direction finding magnetic compasses count on this rule to operate. The ‘north pole’ that a magnet takes this name due to the fact that it constantly points towards the earth north geographic magnetic pole.Similar magnetic poles repel and unlike magnetic poles attract each other.
Critical to teach ideasMagnetic forces are non contact forces; they pull or press on objects without poignant them.Magnets are just attracted come a few ‘magnetic’ metals and also not all matter.Magnets room attracted to and repel other magnets.
At standards up to and including Level 3, that is proper to encourage students come observe and explore magnetic phenomena through play. Students have to be assisted to develop simple understandings the the observed attraction the magnets to some ‘special’ metals (not every metals) and also their attraction and also repulsion to various other magnets. Students need to be motivated to discriminate between magnetic forces, electrostatic and also gravitational forces as being various to each other yet examples of pressures that have the right to act without physical call taking ar i.e. Examples of non contact forces.
Provide one open trouble to be explored via play or through difficulty solving
Provide students v a variety of different materials because that them to inspection which ones have magnetic properties. This materials could include samples of: paper, plastic, polystyrene, wood, glass, rope, leaves, ceramic, rock, and also some objects make of iron or steel. Look to use just metallic objects make from steel or stole so students can see the being composed of a solid metallic product 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 fridge magnet to check out which ones space attracted come the magnet. Ask castle to sort the objects right into two different groups: those that show up to be attractive to a magnet and those which perform not.
Invite the students to sell suggestions of common features of the objects in the group that were attracted come the magnet. Is it your colour, load or the problem they room made that that might make the difference? have actually students suggest and also test their concepts to identify possible common properties.
After sorting the objects students can then check them to check out if they have actually correctly guess which materials are magnetic.
The intention right here is to encourage students come test miscellaneous materials and through investigation recognise that just a few metals have magnetic properties. Critical point to be made is that in our daily experience many metals appear to be magnetic due to the fact that the most widely used steel is stole containing iron.
Open up discussion via a common experience
Most student are acquainted with magnets ‘attracting’ magnetic products or being attracted to some metallic surfaces such together fridges and also white boards, yet they are far less familiar with magnetic forces that repel every other. This is do more an overwhelming for students come explore due to the fact that they must have actually at the very least two magnets of equivalent strength and also many that the familiar advertising refrigerator magnets used for basic investigations room weak and constructed in a way that they have actually no identifiable magnetic poles.
Try to achieve a variety of ‘fish tank’ glass cleaning magnets i beg your pardon are supplied in bag or ‘cow magnets’ available from some farming produce stores. The surfaces of these magnets room well protected and also will alleviate the risk of student accidentally pinching finger or the magnets shedding pieces if handled roughly.
Ask the student to investigate what they have to do to make the magnets attract and also repel each other. Have them identify various ends of each magnet v identifying stickers. Exactly how well deserve to the students suspect what will occur when the magnets are brought near to each other?
Now encourage students to use masking ice cream to fix one magnet ~ above the roof that a toy car. Usage the hand organized magnet to push the automobile along without emotional it or to entice the automobile towards that by changing its orientation. Deserve to students suspect if the magnet ~ above the automobile will be attracted or repelled by the strategy of a new magnet?
The intention here is for students to recognise the magnets have the right to repel and also attract each other. At this level the is not taken into consideration important for students to be able to recall that prefer poles repel and also unlike poles attract, however to recognise the magnets deserve to repel and attract there is no making physics contact and also that their orientation is important.
Open discussion via a common experience
Have the students for sure a magnet to a stand or the top of a little water bottle making use of some ‘blue tack’ or adhesive ice cream so it overhangs the side challenge of the bottle. Next have them fix a file clip come a size of noodle with sufficient length to reach from the table optimal to the magnet. Finally use some ‘blue tack’ to fix the noodle to the table therefore the file clip is just quick of getting to the magnet and appears suspended in mid air through a gap between it and also the magnet.
The intention right here is for students to observe that magnetic forces will continue to be unhindered and can travel through most products without any effect.
Helping student workout several of the ‘scientific’ explanations for themselves
Collect a variety of uncoated wire coat hangers and cut and straighten castle into short lengths which selection from 10cm to 20cm long. Distribute a pair of these approximately to students functioning in bag or triplets, making certain they room given different sized lengths. Also pass about a number (5 come 8) of tiny paperclips to each group. Deliberately perform not happen out any type of magnets just yet to avoid students bringing them into call with the cable lengths.
Encourage the student to investigate if any type of of the lengths the wire space successful in attracting any of the paperclips. If the cable lengths have not do previous call with any magnets climate they should display no magnetic properties and also not disturb the paperclips.
Now pass the end a irreversible magnet to each of the student groups and demonstrate just how you have the right to use one finish of the magnet to stroke the wire length consistently in one direction resulting in it to become magnetised. Students have the right to then repeat this v their own lengths of wire and determine if they have been successful in making a magnet by testing its capacity to attract or elevator up numerous paperclips.
This method of magnetisation is consistent with the idea of making use of a magnetic field (from the magnet) to progressively align the direction that the atoms acting as tiny magnets in the wire. Share this explanation through students is not recommended.
Have students explain what they did and also discuss just how successful they to be in making a magnet.
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Collecting evidence and data because that analysis
After college student have effectively made one size of wire right into a irreversible magnet, collection them the difficulty of make the most powerful magnet they can. They can again test their success by attracting and lifting as countless of the paperclips as they can with their wire magnets. Have actually students indigenous each team record the number of paperclips your magnet deserve to lift. Encourage students come investigate various properties that the wires the may contribute to making better magnets e.g. To compare the variety of times each was stroked, the size of the wires and the methods used to stroke each wire.