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Science 11th grade
LEARNING UNIT
How are we transforming
our planet?
S/K
Language
Socio cultural context of
the LO
Curricular axis
Standard competencies
Background Knowledge
English Review topic
Glossary
LEARNING OBJECT
What are the physics theories needed for constructing
a Maglev train?
Sk 1: To establish the relationships between Newton's
law of universal gravitation and Coulomb's law.
Sk 2: To establish the relationships between magnetic
field, electric field, and the force affecting charged
particles in movement and at rest.
Sk 3: To represent electric and magnetic fields through
field lines.
Sk 4: To explain how electric current is generated from
a variable magnetic field.
Sk 5: To explain the relationship between
gravitational field and electric field.
English
Colombia
Our physical environment
To explain the forces between bodies as interactions
determined by electric charge and mass.
 Electric charge
 Newton's law of universal gravitation
 Scientific notation
 Force



Electric field: a vector field that associates to each
point in space the Coulomb force experienced by a
unit electric charge.
Retrieved
on
24/06/2016
https://en.wikipedia.org/wiki/Electric_field
from
Retrieved
on
24/06/2016
https://en.wikipedia.org/wiki/Magnetic_field
from
Retrieved
on
24/06/2016
https://en.wikipedia.org/wiki/Electromagnetism
from
Magnetic field: the magnetic effect of electric
currents and magnetic materials.
Electromagnetism: a branch of physics which
involves the study of the electromagnetic force, a
type of physical interaction that occurs between
electrically charged particles.

Levitation: the process by which an object is held
aloft, without mechanical support, in a stable
position.
Retrieved
on
24/06/2016
https://en.wikipedia.org/wiki/Levitation
from
English review topic

Expressing similarity and contrast
Vocabulary box

Maglev: a type of high-speed train that runs on
magnets supported by a magnetic field generated
around the track : from mag (netic) lev (itation).
Compass:
an
instrument
for
determining
directions, as by means of a freely rotating
magnetized needle that indicates magnetic north.
Coil: a conductor, as a copper wire, wound up in a
spiral or other form.
Junkyard: a yard for the collection, storage, and
resale of junk.
Harness: to bring under conditions for effective
use; gain control over for a particular end.




Retrieved on 25/06/2016 from http://www.dictionary.com
NAME: _________________________________________________
GRADE: ________________________________________________
Introduction
A train without wheels
There are trains that do not need wheels to move called Maglev trains,
using electromagnetic properties to advance, and to suspend them 15cm
above the rails.
Figure 2. Taken from http://www.productosjorpi.es/COLEGIOS/Talleres/Sabesque/Trenes-sin-ruedas
As there is no contact with the rails, there is no friction, and so no energy
loss to heat, nor vibration in the train cars. This enables the train to reach
high velocities in a comfortable manner. We might ask ourselves, which
physics theories are critical to engineering a Maglev train?
Objectives
1. To interpret and establish the relationships between electric and
magnetic phenomena.
2. To create graphic representations of the manifestations of electric
and magnetic fields.
3. To describe electromagnetic phenomena and their relationships to
other physical phenomena.
Activity 1
Sk 1: To establish the relationships between Newton's law of universal
gravitation and Coulomb's law.
Sk 2: To explain the relationships between gravitational field and electric
field.
Electric forces
Gravitational force
Before speaking of electric forces, we will recall Newton's law of universal
gravitation; it states that the force of attraction between two particles is
directly proportional to the product of their masses and inversely
proportional to the square of the distance between them.
Coulomb's law
The electric forces, analogous to the gravitational ones, show a
proportional pattern regarding the distance between charged particles.
This pattern is named Coulomb's law after 18th-century French physicist
Charles Coulomb.
Figure 4. Taken from: https://es.wikipedia.org/wiki/Charles-Augustin_de_Coulomb
Similar to Newton's law of universal gravitation, Coulomb's law declares
that the force present between two charges 𝑞1 = 4𝜇𝐶 and 𝑞2 = −8𝜇𝐶 varies
in direct accord with the product of the charges, and inversely with respect
to the square of the distance r between them. It can be expressed
mathematically as follows:
One difference between Coulomb's law and the law of universal
gravitation is that the former also contemplates a repelling force between
like-signed charges. Conversely, when the charges have opposite signs,
they force is attractive. When the force is attractive, it will have a
negative sign; when the force is repulsive, it will have a positive sign.
The unit of measure for electric charge is coulomb, and its unit symbol
is C.
1C is equivalent to the charge of 6,25 × 1018 electrons, and k is the
proportional constant.
Example:
Two charges 𝑞1 = 4𝜇𝐶 and 𝑞2 = −8𝜇𝐶 are 4mm apart.
Let us solve the following:

Are the charges repelled from or attracted to one another?

By how much force?
Solution:
- Attracted, since they have opposite charges.
- According to the given information:
𝑞1 = 4𝜇𝐶 = 4 × 10−6 𝐶
𝑞2 = −8𝜇𝐶 = −8 × 10−6 𝐶
𝑟 = 4𝑚𝑚 = 4 × 10−3 𝑚
𝑘 = 9 × 109 𝑁. 𝑚2 /𝐶 2
𝑚2
𝐹=
9×109 𝑁. 2 .(4×10−6 𝐶).(−8×10−6 𝐶)
𝐶
(4×10−3 𝑚)2
= −18000
Learning activity
1. Fill in the missing words in the following sentences:

Coulomb's law establishes a proportion to the ______ between
charges.
 The electric force is much stronger than the ________ force.
 The coulomb (C) is a unit of measure that determines the number
of _________ charging an object.
2. Using Coulomb's law, calculate the forces present on the following
charges and indicate whether they are attractive or repulsive:
 𝑞1 = 3𝜇𝐶 𝑞2 = −8𝜇𝐶
𝑟 =2m Answer: -0,054 N attractive force.

𝑞1 = 60𝜇𝐶 𝑞2 = 36𝜇𝐶
Remember that…
𝑑 =30mm
Answer: 7000 N repulsive force
Due to the fact that there are no naturally occurring elements with the
charge 1C, we always use fractions, i.e.:
micro-coulomb= 𝜇𝐶 = 1𝐶 × 10−6
nano-coulomb=nC= 1𝐶 × 10−9
pico-coulomb=pC=1 𝐶 × 10−12
Activity 2
Sk 3: To represent electric and magnetic fields through field lines.
Sk 4: To explain how electric current is generated from a variable
magnetic field.
Sk 5: To explain the relationships between gravitational field and electric
field.
Magnetism
As regards electricity, electric forces are not all there is, we also deal with
magnetic forces. These two are directly related to one another.
The effect of magnetic forces is readily observed in magnets. By means
of these forces, magnets attract certain metals and other magnets.
Magnetic force is generated by the movement of electrically charged
particles. Just like electric force, magnetism is also influenced by the
distance between the magnetically charged objects.
Metals are not the only magnets; our planet also constitutes a giant
magnet. A compass works because of Earth's magnetic field, the needle
being attracted to the magnetism present at the North magnetic pole.
This same magnetism is used by certain birds to orient themselves in their
migratory flights.
Figure 8. Taken from https://elsecretodelospajaros.wordpress.com/category/el-vuelode-las-aves/
Magnetic poles
As is the case with electric forces, magnetic forces also attract or repel.
These interactions take place firstly in the charged particles, while
magnetism occurs in areas called magnetic poles.
Two types of magnetic poles exist: north and south. Analogous to
charges, opposite poles attract and equal poles repulse. All magnets
possess one north and one south pole.
In electric forces, the charges are independent elements. Every charge
(positive and negative) may exist without its opposite. Magnetism is
different; a north pole can never exist without a south pole, and vice
versa. That is to say, a magnet always has a north pole and a south
pole.
Unlike electricity, due to this inherency magnetism cannot be isolated.
Electric and magnetic fields
The regions of space that are influenced by electric and magnetic forces
are called electric fields and magnetic fields, respectively.
The easiest way to describe these types of fields is through lines
representing the forces generated in these situations.
In the case of an electric field, it can be considered as a point charge, or
as an interaction between charges.
Figure 9. Taken from http://javieraelectricidad.blogspot.com.co/2010/08/camposelectrico-y-magnetico.html
We may notice that in positive charges, the forces work outside the
charge, whereas in negative charges they work toward its interior. This is
the reason opposite charges interact with and attract each other, while
equal charges repel.
The lines in magnetic fields are represented in the following manner:
Figure 10. Taken from http://jacobo.tarrio.org/es/know/como-funcionan-las-tarjetasde-banda-magnetica
In this type of field, the existence of both poles is essential; if this was
not the case, the field would not exist (in difference to electric fields).
Electromagnets
An electromagnet is a magnet produced by running electric current
through a wire coil. As there is a movement of charged particles through
the wire, as we explained earlier, this generates magnetic forces.
Figure 11. Taken from
http://magnetismo0.webnode.es/investigaciones/electroimanes/
Electromagnets can be so powerful they can be used in junkyards to life
heavy metal objects, even cars.
Maglev trains
1. Rail: Actually constitutes the motor of the train. It is a linear system
of electromagnets that constantly switch polarity.
2. Superconducting magnet: Another electromagnet that utilizes
the power in superconducting metals in order to generate magnetic
force. Due to the changing polarity of the rail, the train can use the
properties of attraction and repulsion to move.
3. Train: Designed aerodynamically to improve its characteristics in
terms of air resistance.
4. Longstator packs: These make up the fixed part of the system
of magnetic suspension. Their function is to transmit power to
their moving counterpart: supporting magnets.
Learning activity
Match the following concepts:
(1)
tism
Magne (1) Force generated by the movement of
electrically charged particles.
(2)
Electro (2) A device generated by electric current.
magnet
(3)
c field
Electri
(3) Area determined by the influence of
electric forces.
Abstract


Electric forces are related to gravitational forces.
Coulomb's law establishes the electric force between charges,
taking into account the distance between them.
 Magnetism is created through the movement of electrically charged
particles.
 There are no magnets with only one pole; the north and south pole
are inherent to the concept.
 The electric and magnetic fields are areas on a plane influenced by
the respective forces.
Homework
Watch the following video and answer the subsequent questions:
[Evans Electric]. (10/02/2008). WORLDS FASTEST TRAINS - MAGLEV
"capable"
of
3,500
km/h
[Embedded
video].
https://www.youtube.com/watch?v=aIwbrZ4knpg

What are the advantages of Maglev trains compared to other types of
trains?

How is magnetic force harnessed for the movement of the train?

What are the disadvantages of the Maglev system?
Evaluation
Answer the following multi choice questions:
1. Coulomb's law states that the electric force between charged particles
is inversely proportional to:
A.
B.
C.
D.
The
The
The
The
charge of the particles.
mass of the particles.
distance between the particles.
square of the distance between the particles.
2. Two spheres with equal charge repel one another when separated by
distance a. When the distance between them doubles, the force is
reduced to:
A. 1 / 4
B. 1 / 6
C. 1 / 9
D. 1 / 12
Indicate true or false for the following statements:
3. There are magnets with only one pole. ( )
4. An electric charge generates an electric field. ( )
5. In magnetism, equal poles do not repel, as opposed to the case of
equally charged electric charges. ( )
Fill in the missing words:
6. An ____________ is a ________ generated by inducing electric
________ through a wire coil.
a. field-magnet-current
b. magnet-current -electromagnet
c. electromagnet-magnet-current
d. field-electromagnet-current
Bibliography



Hewitt, P. (2004). Física Conceptual . México : Pearson Educación.
Lewis, T. (2015). What is Magnetism? Livescience. Retrieved from:
http://www.livescience.com/38059-magnetism.html
(S.a). (s.a). Electric Field Lines. Physics Classroom. Retrieved from:
http://www.physicsclassroom.com/class/estatics/Lesson4/Electric-Field-Lines