{"id":1213,"date":"2017-10-27T16:31:40","date_gmt":"2017-10-27T16:31:40","guid":{"rendered":"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/chapter\/magnets\/"},"modified":"2017-11-08T03:26:35","modified_gmt":"2017-11-08T03:26:35","slug":"magnets","status":"publish","type":"chapter","link":"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/chapter\/magnets\/","title":{"raw":"Magnets","rendered":"Magnets"},"content":{"raw":"\n<div class=\"textbox learning-objectives\">\n<h3 itemprop=\"educationalUse\">Learning Objectives<\/h3>\n<ul>\n<li>Describe the difference between the north and south poles of a magnet.<\/li>\n<li>Describe how magnetic poles interact with each other.<\/li>\n<\/ul>\n<\/div>\n<div class=\"bc-figure figure\" id=\"import-auto-id1750359\">\n<div class=\"bc-figcaption figcaption\">Magnets come in various shapes, sizes, and strengths. All have both a north pole and a south pole. There is never an isolated pole (a monopole).<\/div>\n<p><span data-type=\"media\" id=\"import-auto-id1704497\" data-alt=\"Bar magnets, horseshoe magnets, and disc-shaped magnets attract and repel each other. Metal paperclips stick to some of the magnets.\"><br>\n        <img src=\"https:\/\/pressbooks.bccampus.ca\/clalonde\/wp-content\/uploads\/sites\/280\/2017\/10\/FIgure_23_01_01a.jpg\" data-media-type=\"image\/wmf\" alt=\"Bar magnets, horseshoe magnets, and disc-shaped magnets attract and repel each other. Metal paperclips stick to some of the magnets.\" width=\"320\"><\/span><\/p><\/div>\n<p id=\"import-auto-id1704838\">All magnets attract iron, such as that in a refrigerator door. However, magnets may attract or repel other magnets. Experimentation shows that all magnets have two poles. If freely suspended, one pole will point toward the north. The two poles are thus named the <span data-type=\"term\" id=\"import-auto-id1655510\">north magnetic pole<\/span> and the <span data-type=\"term\" id=\"import-auto-id1413682\">south magnetic pole<\/span> (or more properly, north-seeking and south-seeking poles, for the attractions in those directions).<\/p>\n<div data-type=\"note\" class=\"note\" data-has-label=\"true\" id=\"fs-id2697648\" data-label=\"\">\n<div data-type=\"title\" class=\"title\">Universal Characteristics of Magnets and Magnetic Poles<\/div>\n<p id=\"import-auto-id1796045\">It is a universal characteristic of all magnets that <em data-effect=\"italics\">like poles repel and unlike poles attract<\/em>. (Note the similarity with electrostatics:  unlike charges attract and like charges repel.)<\/p>\n<p id=\"import-auto-id1338289\">Further experimentation shows that it is <em data-effect=\"italics\">impossible to separate north and south poles<\/em> in the manner that + and \u2212 charges can be separated.<\/p>\n<\/div>\n<div class=\"bc-figure figure\" id=\"import-auto-id945200\">\n<div class=\"bc-figcaption figcaption\">One end of a bar magnet is suspended from a thread that points toward north. The magnet\u2019s two poles are labeled N and S for north-seeking and south-seeking poles, respectively.<\/div>\n<p><span data-type=\"media\" id=\"import-auto-id1645429\" data-alt=\"A globe of the Earth with a bar magnet inside it. The south pole of the bar magnet inside the globe is at the north magnetic pole and is near, but not exactly on, the north geographic pole. The north pole of the bar magnet inside the globe is near the south geographic pole. Another bar magnet hangs beside the globe. The north pole of this magnet is pointing toward the north pole of the globe (or the south pole of the magnet inside the globe).\"><br>\n        <img src=\"https:\/\/pressbooks.bccampus.ca\/clalonde\/wp-content\/uploads\/sites\/280\/2017\/10\/Figure_23_01_02a.jpg\" data-media-type=\"image\/jpg\" alt=\"A globe of the Earth with a bar magnet inside it. The south pole of the bar magnet inside the globe is at the north magnetic pole and is near, but not exactly on, the north geographic pole. The north pole of the bar magnet inside the globe is near the south geographic pole. Another bar magnet hangs beside the globe. The north pole of this magnet is pointing toward the north pole of the globe (or the south pole of the magnet inside the globe).\" width=\"250\"><\/span><\/p><\/div>\n<div data-type=\"note\" class=\"note\" data-has-label=\"true\" id=\"eip-21\" data-label=\"\">\n<div data-type=\"title\" class=\"title\">Misconception Alert: Earth\u2019s Geographic North Pole Hides an S<\/div>\n<p id=\"eip-id1847606\">The Earth acts like a very large bar magnet with its south-seeking pole near the geographic North Pole. That is why the north pole of your compass is attracted toward the geographic north pole of the Earth\u2014because the magnetic pole that is near the geographic North Pole is actually a south magnetic pole! Confusion arises because the geographic term \u201cNorth Pole\u201d has come to be used (incorrectly) for the magnetic pole that is near the North Pole. Thus, \u201cNorth magnetic pole\u201d is actually a misnomer\u2014it should be called the South magnetic pole.<\/p>\n<\/div>\n<div class=\"bc-figure figure\" id=\"import-auto-id2869574\">\n<div class=\"bc-figcaption figcaption\">Unlike poles attract, whereas like poles repel.<\/div>\n<p><span data-type=\"media\" id=\"import-auto-id2018271\" data-alt=\"Two sets of bar magnets. The first set of magnets are oriented with the unlike poles adjacent to each other. Force arrows show that these magnets are pulling on each other. The second set of magnets is oriented with the like poles adjacent to each other. Force arrows show that these magnets are pushing each other away.\"><br>\n        <img src=\"https:\/\/pressbooks.bccampus.ca\/clalonde\/wp-content\/uploads\/sites\/280\/2017\/10\/Figure_23_01_03a.jpg\" data-media-type=\"image\/jpg\" alt=\"Two sets of bar magnets. The first set of magnets are oriented with the unlike poles adjacent to each other. Force arrows show that these magnets are pulling on each other. The second set of magnets is oriented with the like poles adjacent to each other. Force arrows show that these magnets are pushing each other away.\" width=\"300\"><\/span><\/p><\/div>\n<div class=\"bc-figure figure\" id=\"import-auto-id1660354\">\n<div class=\"bc-figcaption figcaption\">North and south poles always occur in pairs. Attempts to separate them result in more pairs of poles. If we continue to split the magnet, we will eventually get down to an iron atom with a north pole and a south pole\u2014these, too, cannot be separated.<\/div>\n<p><span data-type=\"media\" id=\"import-auto-id2069163\" data-alt=\"A bar magnet is split in half several times. The original magnet has a south pole and a north pole. Each time the magnet is split, each new half has both a south pole and a north pole.\"><br>\n        <img src=\"https:\/\/pressbooks.bccampus.ca\/clalonde\/wp-content\/uploads\/sites\/280\/2017\/10\/Figure_23_01_04a.jpg\" data-media-type=\"image\/jpg\" alt=\"A bar magnet is split in half several times. The original magnet has a south pole and a north pole. Each time the magnet is split, each new half has both a south pole and a north pole.\" width=\"200\"><\/span><\/p><\/div>\n<p id=\"import-auto-id1772073\">The fact that magnetic poles always occur in pairs of north and south is true from the very large scale\u2014for example, sunspots always occur in pairs that are north and south magnetic poles\u2014all the way down to the very small scale. Magnetic atoms have both a north pole and a south pole, as do many types of subatomic particles, such as electrons, protons, and neutrons.<\/p>\n<div data-type=\"note\" class=\"note\" data-has-label=\"true\" id=\"fs-id2019281\" data-label=\"\">\n<div data-type=\"title\" class=\"title\">Making Connections: Take-Home Experiment\u2014Refrigerator Magnets<\/div>\n<p id=\"import-auto-id1934443\">We know that like magnetic poles repel and unlike poles attract. See if you can show this for two refrigerator magnets. Will the magnets stick if you turn them over? Why do they stick to the door anyway? What can you say about the magnetic properties of the door next to the magnet? Do refrigerator magnets stick to metal or plastic spoons? Do they stick to all types of metal?<\/p>\n<\/div>\n<div class=\"section-summary\" data-depth=\"1\" id=\"fs-id1957509\">\n<h1 data-type=\"title\">Section Summary<\/h1>\n<ul id=\"fs-id2688725\">\n<li>Magnetism is a subject that includes the properties of magnets, the effect of the magnetic force on moving charges and currents, and the creation of magnetic fields by currents.<\/li>\n<li>There are two types of magnetic poles, called the north magnetic pole and south magnetic pole.<\/li>\n<li>North magnetic poles are those that are attracted toward the Earth\u2019s geographic north pole.<\/li>\n<li>Like poles repel and unlike poles attract.<\/li>\n<li>Magnetic poles always occur in pairs of north and south\u2014it is not possible to isolate north and south poles.<\/li>\n<\/ul>\n<\/div>\n<div class=\"conceptual-questions\" data-depth=\"1\" id=\"fs-id2603660\" data-element-type=\"conceptual-questions\">\n<h1 data-type=\"title\">Conceptual Questions<\/h1>\n<div data-type=\"exercise\" class=\"exercise\" id=\"fs-id1735677\" data-element-type=\"conceptual-questions\">\n<div data-type=\"problem\" class=\"problem\" id=\"fs-id1907606\">\n<p id=\"import-auto-id2150309\">Volcanic and other such activity at the mid-Atlantic ridge extrudes material to fill the gap between separating tectonic plates associated with continental drift. The magnetization of rocks is found to reverse in a coordinated manner with distance from the ridge. What does this imply about the Earth\u2019s magnetic field and how could the knowledge of the spreading rate be used to give its historical record?<\/p>\n<\/div>\n<\/div>\n<\/div>\n<div data-type=\"glossary\" class=\"textbox shaded\">\n<h2 data-type=\"glossary-title\">Glossary<\/h2>\n<dl class=\"definition\" id=\"import-auto-id1896961\">\n<dt>north magnetic pole<\/dt>\n<dd id=\"fs-id2418896\">the end or the side of a magnet that is attracted toward Earth\u2019s geographic north pole<\/dd>\n<\/dl>\n<dl class=\"definition\" id=\"import-auto-id2571598\">\n<dt>south magnetic pole<\/dt>\n<dd id=\"fs-id1735157\">the end or the side of a magnet that is attracted toward Earth\u2019s geographic south pole<\/dd>\n<\/dl>\n<\/div>\n\n","rendered":"<div class=\"textbox learning-objectives\">\n<h3 itemprop=\"educationalUse\">Learning Objectives<\/h3>\n<ul>\n<li>Describe the difference between the north and south poles of a magnet.<\/li>\n<li>Describe how magnetic poles interact with each other.<\/li>\n<\/ul>\n<\/div>\n<div class=\"bc-figure figure\" id=\"import-auto-id1750359\">\n<div class=\"bc-figcaption figcaption\">Magnets come in various shapes, sizes, and strengths. All have both a north pole and a south pole. There is never an isolated pole (a monopole).<\/div>\n<p><span data-type=\"media\" id=\"import-auto-id1704497\" data-alt=\"Bar magnets, horseshoe magnets, and disc-shaped magnets attract and repel each other. Metal paperclips stick to some of the magnets.\"><br \/>\n        <img decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/clalonde\/wp-content\/uploads\/sites\/280\/2017\/10\/FIgure_23_01_01a.jpg\" data-media-type=\"image\/wmf\" alt=\"Bar magnets, horseshoe magnets, and disc-shaped magnets attract and repel each other. Metal paperclips stick to some of the magnets.\" width=\"320\" \/><\/span><\/p>\n<\/div>\n<p id=\"import-auto-id1704838\">All magnets attract iron, such as that in a refrigerator door. However, magnets may attract or repel other magnets. Experimentation shows that all magnets have two poles. If freely suspended, one pole will point toward the north. The two poles are thus named the <span data-type=\"term\" id=\"import-auto-id1655510\">north magnetic pole<\/span> and the <span data-type=\"term\" id=\"import-auto-id1413682\">south magnetic pole<\/span> (or more properly, north-seeking and south-seeking poles, for the attractions in those directions).<\/p>\n<div data-type=\"note\" class=\"note\" data-has-label=\"true\" id=\"fs-id2697648\" data-label=\"\">\n<div data-type=\"title\" class=\"title\">Universal Characteristics of Magnets and Magnetic Poles<\/div>\n<p id=\"import-auto-id1796045\">It is a universal characteristic of all magnets that <em data-effect=\"italics\">like poles repel and unlike poles attract<\/em>. (Note the similarity with electrostatics:  unlike charges attract and like charges repel.)<\/p>\n<p id=\"import-auto-id1338289\">Further experimentation shows that it is <em data-effect=\"italics\">impossible to separate north and south poles<\/em> in the manner that + and \u2212 charges can be separated.<\/p>\n<\/div>\n<div class=\"bc-figure figure\" id=\"import-auto-id945200\">\n<div class=\"bc-figcaption figcaption\">One end of a bar magnet is suspended from a thread that points toward north. The magnet\u2019s two poles are labeled N and S for north-seeking and south-seeking poles, respectively.<\/div>\n<p><span data-type=\"media\" id=\"import-auto-id1645429\" data-alt=\"A globe of the Earth with a bar magnet inside it. The south pole of the bar magnet inside the globe is at the north magnetic pole and is near, but not exactly on, the north geographic pole. The north pole of the bar magnet inside the globe is near the south geographic pole. Another bar magnet hangs beside the globe. The north pole of this magnet is pointing toward the north pole of the globe (or the south pole of the magnet inside the globe).\"><br \/>\n        <img decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/clalonde\/wp-content\/uploads\/sites\/280\/2017\/10\/Figure_23_01_02a.jpg\" data-media-type=\"image\/jpg\" alt=\"A globe of the Earth with a bar magnet inside it. The south pole of the bar magnet inside the globe is at the north magnetic pole and is near, but not exactly on, the north geographic pole. The north pole of the bar magnet inside the globe is near the south geographic pole. Another bar magnet hangs beside the globe. The north pole of this magnet is pointing toward the north pole of the globe (or the south pole of the magnet inside the globe).\" width=\"250\" \/><\/span><\/p>\n<\/div>\n<div data-type=\"note\" class=\"note\" data-has-label=\"true\" id=\"eip-21\" data-label=\"\">\n<div data-type=\"title\" class=\"title\">Misconception Alert: Earth\u2019s Geographic North Pole Hides an S<\/div>\n<p id=\"eip-id1847606\">The Earth acts like a very large bar magnet with its south-seeking pole near the geographic North Pole. That is why the north pole of your compass is attracted toward the geographic north pole of the Earth\u2014because the magnetic pole that is near the geographic North Pole is actually a south magnetic pole! Confusion arises because the geographic term \u201cNorth Pole\u201d has come to be used (incorrectly) for the magnetic pole that is near the North Pole. Thus, \u201cNorth magnetic pole\u201d is actually a misnomer\u2014it should be called the South magnetic pole.<\/p>\n<\/div>\n<div class=\"bc-figure figure\" id=\"import-auto-id2869574\">\n<div class=\"bc-figcaption figcaption\">Unlike poles attract, whereas like poles repel.<\/div>\n<p><span data-type=\"media\" id=\"import-auto-id2018271\" data-alt=\"Two sets of bar magnets. The first set of magnets are oriented with the unlike poles adjacent to each other. Force arrows show that these magnets are pulling on each other. The second set of magnets is oriented with the like poles adjacent to each other. Force arrows show that these magnets are pushing each other away.\"><br \/>\n        <img decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/clalonde\/wp-content\/uploads\/sites\/280\/2017\/10\/Figure_23_01_03a.jpg\" data-media-type=\"image\/jpg\" alt=\"Two sets of bar magnets. The first set of magnets are oriented with the unlike poles adjacent to each other. Force arrows show that these magnets are pulling on each other. The second set of magnets is oriented with the like poles adjacent to each other. Force arrows show that these magnets are pushing each other away.\" width=\"300\" \/><\/span><\/p>\n<\/div>\n<div class=\"bc-figure figure\" id=\"import-auto-id1660354\">\n<div class=\"bc-figcaption figcaption\">North and south poles always occur in pairs. Attempts to separate them result in more pairs of poles. If we continue to split the magnet, we will eventually get down to an iron atom with a north pole and a south pole\u2014these, too, cannot be separated.<\/div>\n<p><span data-type=\"media\" id=\"import-auto-id2069163\" data-alt=\"A bar magnet is split in half several times. The original magnet has a south pole and a north pole. Each time the magnet is split, each new half has both a south pole and a north pole.\"><br \/>\n        <img decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/clalonde\/wp-content\/uploads\/sites\/280\/2017\/10\/Figure_23_01_04a.jpg\" data-media-type=\"image\/jpg\" alt=\"A bar magnet is split in half several times. The original magnet has a south pole and a north pole. Each time the magnet is split, each new half has both a south pole and a north pole.\" width=\"200\" \/><\/span><\/p>\n<\/div>\n<p id=\"import-auto-id1772073\">The fact that magnetic poles always occur in pairs of north and south is true from the very large scale\u2014for example, sunspots always occur in pairs that are north and south magnetic poles\u2014all the way down to the very small scale. Magnetic atoms have both a north pole and a south pole, as do many types of subatomic particles, such as electrons, protons, and neutrons.<\/p>\n<div data-type=\"note\" class=\"note\" data-has-label=\"true\" id=\"fs-id2019281\" data-label=\"\">\n<div data-type=\"title\" class=\"title\">Making Connections: Take-Home Experiment\u2014Refrigerator Magnets<\/div>\n<p id=\"import-auto-id1934443\">We know that like magnetic poles repel and unlike poles attract. See if you can show this for two refrigerator magnets. Will the magnets stick if you turn them over? Why do they stick to the door anyway? What can you say about the magnetic properties of the door next to the magnet? Do refrigerator magnets stick to metal or plastic spoons? Do they stick to all types of metal?<\/p>\n<\/div>\n<div class=\"section-summary\" data-depth=\"1\" id=\"fs-id1957509\">\n<h1 data-type=\"title\">Section Summary<\/h1>\n<ul id=\"fs-id2688725\">\n<li>Magnetism is a subject that includes the properties of magnets, the effect of the magnetic force on moving charges and currents, and the creation of magnetic fields by currents.<\/li>\n<li>There are two types of magnetic poles, called the north magnetic pole and south magnetic pole.<\/li>\n<li>North magnetic poles are those that are attracted toward the Earth\u2019s geographic north pole.<\/li>\n<li>Like poles repel and unlike poles attract.<\/li>\n<li>Magnetic poles always occur in pairs of north and south\u2014it is not possible to isolate north and south poles.<\/li>\n<\/ul>\n<\/div>\n<div class=\"conceptual-questions\" data-depth=\"1\" id=\"fs-id2603660\" data-element-type=\"conceptual-questions\">\n<h1 data-type=\"title\">Conceptual Questions<\/h1>\n<div data-type=\"exercise\" class=\"exercise\" id=\"fs-id1735677\" data-element-type=\"conceptual-questions\">\n<div data-type=\"problem\" class=\"problem\" id=\"fs-id1907606\">\n<p id=\"import-auto-id2150309\">Volcanic and other such activity at the mid-Atlantic ridge extrudes material to fill the gap between separating tectonic plates associated with continental drift. The magnetization of rocks is found to reverse in a coordinated manner with distance from the ridge. What does this imply about the Earth\u2019s magnetic field and how could the knowledge of the spreading rate be used to give its historical record?<\/p>\n<\/div>\n<\/div>\n<\/div>\n<div data-type=\"glossary\" class=\"textbox shaded\">\n<h2 data-type=\"glossary-title\">Glossary<\/h2>\n<dl class=\"definition\" id=\"import-auto-id1896961\">\n<dt>north magnetic pole<\/dt>\n<dd id=\"fs-id2418896\">the end or the side of a magnet that is attracted toward Earth\u2019s geographic north pole<\/dd>\n<\/dl>\n<dl class=\"definition\" id=\"import-auto-id2571598\">\n<dt>south magnetic pole<\/dt>\n<dd id=\"fs-id1735157\">the end or the side of a magnet that is attracted toward Earth\u2019s geographic south pole<\/dd>\n<\/dl>\n<\/div>\n","protected":false},"author":211,"menu_order":1,"template":"","meta":{"pb_show_title":"on","pb_short_title":"","pb_subtitle":"","pb_authors":[],"pb_section_license":"all-rights-reserved"},"chapter-type":[],"contributor":[],"license":[56],"class_list":["post-1213","chapter","type-chapter","status-publish","hentry","license-all-rights-reserved"],"part":1204,"_links":{"self":[{"href":"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-json\/pressbooks\/v2\/chapters\/1213","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-json\/pressbooks\/v2\/chapters"}],"about":[{"href":"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-json\/wp\/v2\/types\/chapter"}],"author":[{"embeddable":true,"href":"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-json\/wp\/v2\/users\/211"}],"version-history":[{"count":1,"href":"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-json\/pressbooks\/v2\/chapters\/1213\/revisions"}],"predecessor-version":[{"id":1214,"href":"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-json\/pressbooks\/v2\/chapters\/1213\/revisions\/1214"}],"part":[{"href":"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-json\/pressbooks\/v2\/parts\/1204"}],"metadata":[{"href":"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-json\/pressbooks\/v2\/chapters\/1213\/metadata\/"}],"wp:attachment":[{"href":"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-json\/wp\/v2\/media?parent=1213"}],"wp:term":[{"taxonomy":"chapter-type","embeddable":true,"href":"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-json\/pressbooks\/v2\/chapter-type?post=1213"},{"taxonomy":"contributor","embeddable":true,"href":"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-json\/wp\/v2\/contributor?post=1213"},{"taxonomy":"license","embeddable":true,"href":"https:\/\/pressbooks.bccampus.ca\/ubcbatessandbox\/wp-json\/wp\/v2\/license?post=1213"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}