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Science: Topics Electromagnetism (view source)
Revision as of 06:10, 24 August 2012
, 06:10, 24 August 2012no edit summary
[[Image:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_b641926.png]]
[[File:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_b641926.png]]
[[Image:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_m1ba34f6e.png]]
[[File:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_m1ba34f6e.png]]
[[Image:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_7fb72f41.png]]Protons
[[File:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_7fb72f41.png]]Protons
are much larger and heavier than electrons. Protons have a positive
are much larger and heavier than electrons. Protons have a positive
electrical charge. This positively charged electrostatic field is
electrical charge. This positively charged electrostatic field is
[[Image:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_51ef531a.png]]The
[[File:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_51ef531a.png]]The
electrostatic force exerted by the positive nucleus on the negatively
electrostatic force exerted by the positive nucleus on the negatively
charged electrons is what keeps the electrons as a part of the atom.
charged electrons is what keeps the electrons as a part of the atom.
[[Image:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_f783dcf.png]]When
[[File:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_f783dcf.png]]When
an electrically charged object is brought near an uncharged object
an electrically charged object is brought near an uncharged object
(the object must be a conductor), a distribution of charge happens in
(the object must be a conductor), a distribution of charge happens in
[[Image:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_m2d4a26f1.gif]]
[[File:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_m2d4a26f1.gif]]
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[[Image:Electron.jpg]]
[[File:Electron.jpg]]
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[[Image:proton.jpg]][[Image:proton.jpg]]
[[File:proton.jpg]][[File:proton.jpg]]
[[Image:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_4b56cbe9.gif]]
[[File:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_4b56cbe9.gif]]
[[Image:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_m2f27def.png]]
[[File:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_m2f27def.png]]
== Voltage sources – batteries and generators ==
== Voltage sources – batteries and generators ==
[[Image:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_bb112d6.png]]A
[[File:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_bb112d6.png]]A
battery or a generator does work to pull electrons from positive
battery or a generator does work to pull electrons from positive
charges. In a battery, this is done using chemical reactions; where
charges. In a battery, this is done using chemical reactions; where
induction.
induction.
[[Image:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_70ab754b.jpg]]
[[File:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_70ab754b.jpg]]
The cell shown here uses dilute sulphuric acid as
The cell shown here uses dilute sulphuric acid as
the electrolyte. One of the electrodes is carbon ; the other is
the electrolyte. One of the electrodes is carbon ; the other is
[[Image:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_m74e99ab1.gif]]
[[File:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_m74e99ab1.gif]]
[[Image:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_m7ebc180f.png]]
[[File:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_m7ebc180f.png]]
The Chinese have known to use Magnetic needles for
The Chinese have known to use Magnetic needles for
navigation on[[Image:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_494fe551.jpg]]
navigation on[[File:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_494fe551.jpg]]
ships since the 12<sup>th</sup> century. In the 16<sup>th</sup>
ships since the 12<sup>th</sup> century. In the 16<sup>th</sup>
century, William Gilbert, Queen Elizabeth's physician made artificial
century, William Gilbert, Queen Elizabeth's physician made artificial
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[[File:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_m4b1bf843.jpg]]
[[Image:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_1e5941a4.jpg]][[Image:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_m78bd27f.jpg]]
[[File:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_1e5941a4.jpg]][[File:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_m78bd27f.jpg]]
The following
The following
diagram depicts the magnetic lines of force between two north pole,
diagram depicts the magnetic lines of force between two north pole,
two south pole; Nort[[Image:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_m378bcdfd.jpg]]h-South
two south pole; Nort[[File:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_m378bcdfd.jpg]]h-South
pole. [[Image:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_63b374f3.jpg]][[Image:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_677bab2f.jpg]]
pole. [[File:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_63b374f3.jpg]][[File:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_677bab2f.jpg]]
* [[Image:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_m7c4d4e3d.jpg]]Magnetic field of Earth may be due to molten charged metallic fluid in core. This rotating fluid results in currents thus magnetising the Earth.
* [[File:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_m7c4d4e3d.jpg]]Magnetic field of Earth may be due to molten charged metallic fluid in core. This rotating fluid results in currents thus magnetising the Earth.
* Since every substance is made up of charged particles, these substances rotating about an axis is equivalent to a circulating current and hence is responsible for the Earth's magnetisation.
* Since every substance is made up of charged particles, these substances rotating about an axis is equivalent to a circulating current and hence is responsible for the Earth's magnetisation.
[[Image:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_m1ef9ebaf.jpg]]The
[[File:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_m1ef9ebaf.jpg]]The
magnetic equator divides the earth's surface into two. The field
magnetic equator divides the earth's surface into two. The field
lines enter geographic north and come out of the geographic south.
lines enter geographic north and come out of the geographic south.
Magnetic declination is the angle between magnetic
Magnetic declination is the angle between magnetic
axis and the geographic axis.[[Image:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_m65aa48a2.jpg]]
axis and the geographic axis.[[File:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_m65aa48a2.jpg]]
[[Image:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_1f7d7930.jpg]][[Image:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_m3142907a.jpg]]
[[File:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_1f7d7930.jpg]][[File:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_m3142907a.jpg]]
[[Image:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_m57cad797.png]][[Image:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_38133c13.png]]
[[File:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_m57cad797.png]][[File:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_38133c13.png]]
Mathematically ''' [[Image:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_7e4eff4e.png]]'''
Mathematically ''' [[File:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_7e4eff4e.png]]'''
where [[Image:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_517f1c9.png]]
where [[File:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_517f1c9.png]]
is the intensity of magnetisation,[[Image:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_m702f710c.png]]net
is the intensity of magnetisation,[[File:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_m702f710c.png]]net
magnetic moment, v the volume of the material.
magnetic moment, v the volume of the material.
[[Image:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_mdd4cec8.png]]
[[File:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_mdd4cec8.png]]
The flux density
The flux density
produced by the magnetising field vacuum is proportional to the
produced by the magnetising field vacuum is proportional to the
intensity of field [[Image:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_ma7650ad.png]].
intensity of field [[File:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_ma7650ad.png]].
This indicates
This indicates
how easily the material can be magnetised. It is represented as X<sub>m</sub>.
how easily the material can be magnetised. It is represented as X<sub>m</sub>.
''' [[Image:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_3c447df9.png]]''' i.e., the
''' [[File:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_3c447df9.png]]''' i.e., the
ratio of intensity of magnetisation induced in the material to
ratio of intensity of magnetisation induced in the material to
magnetising field (H).
magnetising field (H).
== Diamagnetic Substance ==
== Diamagnetic Substance ==
[[Image:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_6577ae4e.jpg]][[Image:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_m5788b4cc.jpg]]Michael
[[File:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_6577ae4e.jpg]][[File:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_m5788b4cc.jpg]]Michael
Faraday discovered that a specimen of bismuth was repelled by a
Faraday discovered that a specimen of bismuth was repelled by a
strong magnet. Diamagnetism occurs in all materials. These materials
strong magnet. Diamagnetism occurs in all materials. These materials
[[Image:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_4e1ff244.jpg]]5)
[[File:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_4e1ff244.jpg]]5)
The permeability of the substance, that is, m<sub>r</sub>
The permeability of the substance, that is, m<sub>r</sub>
< 1.
< 1.
[[Image:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_m1b102b1d.jpg]]The
[[File:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_m1b102b1d.jpg]]The
vector sum of the individual dipole moments is no longer zero.
vector sum of the individual dipole moments is no longer zero.
* When a paramagnetic rod is suspended freely in a uniform magnetic field, it aligns itself in the direction of magnetic field.
* When a paramagnetic rod is suspended freely in a uniform magnetic field, it aligns itself in the direction of magnetic field.
* [[Image:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_33c219a8.jpg]]The lines of force prefer to pass through the material rather than air that is m<sub>r</sub> > 1 that is their permeability is greater than one.
* [[File:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_33c219a8.jpg]]The lines of force prefer to pass through the material rather than air that is m<sub>r</sub> > 1 that is their permeability is greater than one.
* As soon as the magnetizing field is removed the paramagnetics lose their magnetization.
* As soon as the magnetizing field is removed the paramagnetics lose their magnetization.
* [[Image:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_m41e0c6c7.jpg]]These substances get strongly magnetized in the direction of field.
* [[File:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_m41e0c6c7.jpg]]These substances get strongly magnetized in the direction of field.
* The lines of force prefer to pass through the material rather than air that is m<sub>r</sub>>1 that is their permeability is greater than one.
* The lines of force prefer to pass through the material rather than air that is m<sub>r</sub>>1 that is their permeability is greater than one.
* [[Image:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_33c219a8.jpg]]In a non-uniform magnetic, the specimen move from weaker parts of the field to the stronger parts (that is it accumulates in the middle).
* [[File:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_33c219a8.jpg]]In a non-uniform magnetic, the specimen move from weaker parts of the field to the stronger parts (that is it accumulates in the middle).
* A paramagnetic liquid in U tube placed between two poles of a magnet is elevated.
* A paramagnetic liquid in U tube placed between two poles of a magnet is elevated.
* [[Image:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_m1962e359.jpg]]For ferromagnetic materials m<sub>r</sub> is very large and so its susceptibility i.e., X<sub>m</sub> is positive.
* [[File:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_m1962e359.jpg]]For ferromagnetic materials m<sub>r</sub> is very large and so its susceptibility i.e., X<sub>m</sub> is positive.
* Ferromagnetic substances retain their magnetism even after the magnetizing field is removed.
* Ferromagnetic substances retain their magnetism even after the magnetizing field is removed.
* The effectiveness of coupling between the neighboring atoms that causes ferromagnetism decreases by increasing the temperature of the substance. The temperature at which a ferromagnetic material becomes paramagnetic is called its curie temperature. For example the curie temperature of iron is 1418<sup>o</sup>F, which means above this temperature, iron is paramagnetic.
* The effectiveness of coupling between the neighboring atoms that causes ferromagnetism decreases by increasing the temperature of the substance. The temperature at which a ferromagnetic material becomes paramagnetic is called its curie temperature. For example the curie temperature of iron is 1418<sup>o</sup>F, which means above this temperature, iron is paramagnetic.
[[Image:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_7825c906.jpg]]Examples
[[File:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_7825c906.jpg]]Examples
are Iron, cobalt, nickel and number of alloys.
are Iron, cobalt, nickel and number of alloys.
[[Image:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_m78bd27f.jpg]][[Image:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_677bab2f.jpg]]
[[File:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_m78bd27f.jpg]][[File:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_677bab2f.jpg]]
[[Image:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_13941b10.png]]The
[[File:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_13941b10.png]]The
strong field produced inside a solenoid can be used to magnetise a
strong field produced inside a solenoid can be used to magnetise a
magnetic material. Such a magnet is called an electromagnet.
magnetic material. Such a magnet is called an electromagnet.
direction is given by [[Fleming's Left-hand rule]]
direction is given by [[Fleming's Left-hand rule]]
and whose magnitude is given by, Force,
and whose magnitude is given by, Force,
[[Image:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_4f2315e8.gif]]
[[File:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_4f2315e8.gif]]
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[[File:motor.3.jpg]]
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[[File:motor.2.jpg]]
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[[File:motor.1.jpg]]
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[[File:motor.2.jpg]]
[[Image:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_8cba5b4.png]]
[[File:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_8cba5b4.png]]
[[Image:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_16468845.png]]
[[File:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_16468845.png]]
[[Image:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_m225205b8.png]]
[[File:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_m225205b8.png]]
[[Image:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_6373b4c9.png]]
[[File:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_6373b4c9.png]]
[[Image:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_m5e53150.png]]
[[File:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_m5e53150.png]]
[[Image:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_23688484.png]]
[[File:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_23688484.png]]
=== The Experiment of Faraday and Henry ===
=== The Experiment of Faraday and Henry ===
[[Image:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_55d6a46f.png]]Faraday
[[File:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_55d6a46f.png]]Faraday
and Henry performed lots of experiments to learn about the connection
and Henry performed lots of experiments to learn about the connection
between electricity and magnetism. The results of these experiments
between electricity and magnetism. The results of these experiments
(ii) The magnitude of the induced EMF is equal to
(ii) The magnitude of the induced EMF is equal to
the rate at which the magnetic flux linked with the circuit changes.[[Image:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_1ac06770.png]]
the rate at which the magnetic flux linked with the circuit changes.[[File:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_1ac06770.png]]
[[Image:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_3e986b27.png]]
[[File:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_3e986b27.png]]
=== Lenz's Law ===
=== Lenz's Law ===
[[Image:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_72319496.png]]
[[File:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_72319496.png]]
[[Image:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_497ddc16.png]]
[[File:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_497ddc16.png]]
[[Image:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_2594d0ac.png]]
[[File:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_2594d0ac.png]]
This
This
way the area of the loop inside the field changes. This induces an
way the area of the loop inside the field changes. This induces an
e.m.f in the wire. If in a small time [[Image:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_m4ce5d5c9.png]],
e.m.f in the wire. If in a small time [[File:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_m4ce5d5c9.png]],
the loop moves a distance [[Image:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_45ce0699.png]],
the loop moves a distance [[File:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_45ce0699.png]],
then the decrease in the area of the loop = - lDx.
then the decrease in the area of the loop = - lDx.
[[Image:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_4c38e4cd.png]]
[[File:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_4c38e4cd.png]]
[[Image:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_7de413e5.png]]where
[[File:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_7de413e5.png]]where
[[Image:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_45406d5c.png]]
[[File:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_45406d5c.png]]
[[Image:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_m68155d35.png]]
[[File:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_m68155d35.png]]
But e.m.f [[Image:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_m598b6616.png]]
But e.m.f [[File:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_m598b6616.png]]
=== Lenz's Law and Energy Conservation ===
=== Lenz's Law and Energy Conservation ===
[[Image:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_2e54c387.png]]
[[File:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_2e54c387.png]]
[[Image:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_m5d4cf08f.jpg]]
[[File:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_m5d4cf08f.jpg]]
Unlike the
Unlike the
metallic wires where the resistance is less metallic [[Image:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_m19b8a684.jpg]]blocks
metallic wires where the resistance is less metallic [[File:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_m19b8a684.jpg]]blocks
have larger resistance and hence the induced currents lead to large
have larger resistance and hence the induced currents lead to large
amount of Joule's heat (H = i<sup>2</sup>k).
amount of Joule's heat (H = i<sup>2</sup>k).
[[Image:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_m7d2a6274.png]]
[[File:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_m7d2a6274.png]]
[[Image:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_195be383.png]]
[[File:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_195be383.png]]
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[[File:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_36e3d4cc.png]]
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[[File:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_7c0bcdea.png]]
[[Image:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_m661b5e87.png]]
[[File:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_m661b5e87.png]]
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[[File:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_4cc6f350.png]]
[[Image:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_7b27b130.png]]
[[File:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_7b27b130.png]]
[[Image:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_m2c4e32ec.png]]
[[File:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_m2c4e32ec.png]]
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f<sub>2</sub>[[Image:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_1bf08989.png]]
f<sub>2</sub>[[File:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_1bf08989.png]]
B<sub>1</sub>A x N<sub>2</sub>
B<sub>1</sub>A x N<sub>2</sub>
[[Image:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_m39eabe5a.png]]
[[File:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_m39eabe5a.png]]
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[[Image:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_17793d1a.png]]
[[File:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_17793d1a.png]]
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[[File:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_m16701510.png]]
'''''Electromagnet''''' tabs for this activity and the
'''''Electromagnet''''' tabs for this activity and the
other tabs later in the unit. Click on the Bar Magnet tab.
other tabs later in the unit. Click on the Bar Magnet tab.
[[Image:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_6bfd456c.png]]
[[File:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_6bfd456c.png]]
* Click on [[Image:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_m7cdbf5e.png]]. Explain the '''two '''changes this causes in the simulation.
* Click on [[File:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_m7cdbf5e.png]]. Explain the '''two '''changes this causes in the simulation.
* M[[Image:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_45126618.png]]ove compass to various locations around the bar magnet. Explain what orientation the needle takes with respect to the bar magnet.
* M[[File:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_45126618.png]]ove compass to various locations around the bar magnet. Explain what orientation the needle takes with respect to the bar magnet.
* S[[Image:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_m4de6ccf7.png]]elect ‘Show Field Meter’ [[Image:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_5242b6c6.png]]. The image below will appear. The meter can be moved to various locations and indicates the magnetic field strength at the crosshairs. '''Label:''' Total magnetic field, y-component of the magnetic field, x-component of the magnetic field, angle and units in the following diagram.
* S[[File:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_m4de6ccf7.png]]elect ‘Show Field Meter’ [[File:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_5242b6c6.png]]. The image below will appear. The meter can be moved to various locations and indicates the magnetic field strength at the crosshairs. '''Label:''' Total magnetic field, y-component of the magnetic field, x-component of the magnetic field, angle and units in the following diagram.
* You should be able to determine the '''direction '''of the magnetic field vector using the meter.
* You should be able to determine the '''direction '''of the magnetic field vector using the meter.
* Select [[Image:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_ma1f6eac.png]]. Observe the orientation of the small compass needles.
* Select [[File:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_ma1f6eac.png]]. Observe the orientation of the small compass needles.
* Click on the Electromagnet tab. [[Image:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_m276d0de7.png]].
* Click on the Electromagnet tab. [[File:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_m276d0de7.png]].
* What is behaving like a magnet : The battery or The coils of current carrying wire ? [[Image:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_m6b8ab73d.png]]
* What is behaving like a magnet : The battery or The coils of current carrying wire ? [[File:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_m6b8ab73d.png]]
* Using the slider on the battery, change the voltage of the battery from 10V to 0V.
* Using the slider on the battery, change the voltage of the battery from 10V to 0V.
Then from 0V to ‘-’ 10V. [[Image:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_m42f9b776.png]]
Then from 0V to ‘-’ 10V. [[File:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_m42f9b776.png]]
* '''G[[Image:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_m519d161e.gif]]etting started.''' Open the website listed above and on the top of the screen select the tab marked electromagnet.
* '''G[[File:Electromagnetism_%20Resource_Material_Subject_Teacher_Forum_September_2011_html_m519d161e.gif]]etting started.''' Open the website listed above and on the top of the screen select the tab marked electromagnet.
* '''Make observations & draw conclusions.''' Change the current source back and forth from DC to AC looking for how the electrons move in the wire. AC current is distinguished from DC current by the motion of the current. In this applet the current is represented by the balls moving in the wire. Based on your observations write a general rule for how current moves in AC verses how current moves in DC.
* '''Make observations & draw conclusions.''' Change the current source back and forth from DC to AC looking for how the electrons move in the wire. AC current is distinguished from DC current by the motion of the current. In this applet the current is represented by the balls moving in the wire. Based on your observations write a general rule for how current moves in AC verses how current moves in DC.
* '''Make observations & draw conclusions.''' Set up the applet so it is using a DC current and place a compass near the electromagnet. Your screen should look something like what you see to the right, on Screen 1. Using the slider on the battery, observe how changing the voltage changes the current flow and what happens to the compass needle. Write down your observations regarding the voltage, the current flow and the change in the compass. What does changing the current flow do to the magnetic field?
* '''Make observations & draw conclusions.''' Set up the applet so it is using a DC current and place a compass near the electromagnet. Your screen should look something like what you see to the right, on Screen 1. Using the slider on the battery, observe how changing the voltage changes the current flow and what happens to the compass needle. Write down your observations regarding the voltage, the current flow and the change in the compass. What does changing the current flow do to the magnetic field?