UNIT 6
ELECTRICITY
Vocabulary
• Ways of generating electricity
• Magnetism & Electromagnetism
• Generators and transformers
Grammar & Functions
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Revision of connectors
Prepositions
Instructions: purpose and method
Integrated practice of grammar and functions
LISTENING: electricity
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Electricity is a phenomenon of SOME CHARGED SUBATOMIC PARTICLES called electrons
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WHEN THEY START MOVING FROM ATOM TO ATOM
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An atom is the smallest particle OF WHICH ALL MATTER IS COMPOSED.
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All atoms consist of a nucleus CONTAINING PROTONS AND NEUTRONS,
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AROUND WHICH ELECTRONS ORBIT;
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electrons orbiting farther from the nucleus ARE MORE EASILY DRAWN AWAY
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therefore are more likely to move and CREATE AN ELECTRIC CURRENT
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thus, AN ELECTRON IS NEGATIVELY CHARGED
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whereas a proton is positively charged and NEUTRONS HAVE NO ELECTRICAL CHARGE
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an atom is electrically neutral AS THERE ARE AS MANY PROTONS AS ELECTRONS IN
ONE ATOM.
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However atoms of different substances DIFFER FROM EACH OTHER DEPENDING ON THE
NUMBER OF ELECTRONS AND PROTONS that they contain.
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IN SPITE OF THE FACT THAT THE NUCLEUS IS THE SMALLEST PART OF AN ATOM,
most of the atom’s weight is concentrated in its nucleus
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An electron, ON THE OTHER HAND, weighs only about 1/1800 (one eighteen hundredth) OF
THE WEIGHT OF A PROTON OR NEUTRON
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Yet to produce the movement of electrons A DIFFERENCE IN POTENTIAL BETWEEN TWO
POINTS must be created.
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Electric sources SUCH AS BATTERIES, CELLS, GENERATORS, etc
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change chemical, mechanical or other types of energy INTO ELECTRICAL ENERGY
CONNECTORS
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WHEREAS/ WHILE
INSTEAD OF
DUE TO THE FACT THAT / SINCE / AS
THUS /THEREFORE
DUE TO
IN SPITE OF / DESPITE
SINCE / DUE TO THE FACT THAT / AS
ALTHOUGH / IN SPITE OF– DESPITE THE FACT THAT
UNLIKE
WHICH
AS
DUE TO
THUS
ALTHOUGH ... THUS (THEREFORE).... INSTEAD
THAT
NOUNS
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ADDition
DIRECTion
STRONG/strength
DEVELOPment
ABLE/ability
ATTRACTion
SCIENCE/scientist
GENERATE/or-tion
MAGNETism
REPEL/repulsion
DISCOVERy
TRANSFORMer/ation
ELECTROMAGNETS
http://www.youtube.com/watch?v=EjfEiEwpuT8
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1-A piece of metal with two ends: North and South
2- A permanent magnet
3- Disadvantages
4- An electromagnet is the same as a permanent magnet
5- We get the N & S poles by passing a current around a wire
wrapped around a coil (e.g. cardboard)
6- I get a North at one end and a South at the other as the current
travels through it
7- I get no magnet
8- Because the electricity creates the magnetism
9 a)There is no metal in it (except the metal in the wire carrying the
current)
9b)If I put in the center some iron it will make it much stronger (1020 times stronger)
9c) A soft iron core (soft= easy to magnetize) =the coil will
magnetize and demagnetize easily
10-I can switch it on and off = to pick up a piece of metal and then
drop it
PREPOSITIONS
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… when brought NEAR a magnet
… attracted BY a magnet are capable OF becoming magnetized
The poles are located AT the ends of the bar magnet.
A Simple Generator consists OF a U-shaped magnet and a single loop of wire
…takes its form AS a result OF intermolecular forces BETWEEN individual
molecules IN matter
The protons are basically trapped INSIDE the nucleus … Therefore, it is moving
electrons….responsible FOR electricity.
Electromagnetism can be used to levitate a train ABOVE the track
WITHOUT electricity our lives would have come to a halt.
…emanate FROM the north …, pass THROUGH surrounding …. … travel
INSIDE the magnet from the south pole TO the north pole
Originally … were thought of AS two separate forces.
… flowing THROUGH a wire …magnetic field AROUND the wire, its direction
depending ON that OF the current.
Some …technologies result IN the creation of solid waste
A generator ..... energy INTO electrical energy. The process is based ON the
relationship BETWEEN magnetism and electricity
Whereas a synchronous motor's rotor turns AT the same rate AS the stator
field, an induction motor's rotor rotates AT a slower speed than the stator field.
PREPOSITIONS
Let´s have a look AT one of Faraday´s experiments, IN which he
used a copper wheel and a horseshoe magnet.
The wheel was located BETWEEN the poles OF the magnet.
Electrical contacts were applied TO the wheel, both AT the centre
and AT the edge of it.
These parts were connected TO an ammeter BY means of wires IN
order to detect the electrical current.
Whenever the wheel rotated BETWEEN the ends of the magnet, an
electrical current was shown ON / IN the ammeter´s display.
When the wheel was made to turn IN the opposite direction, the
needle OF the ammeter was deflected IN the opposite direction,
too.
Therefore, according TO this experiment, the direction of the
current depended ON the turning of the wheel placed close TO
a magnetic field.
VIDEO1: MAGNETIC CIRCUITS (p77)
• This is the well known display of THE MAGNETIC
FIELD of a permanent magnet displayed BY the
DISTRIBUTION of iron filings.
• The whole of this programme is ABOUT displaying
MAGNETIC FIELDS in one way or another.
• Of course the trouble with magnetic fields is that you
cannot actually see them. So, what I'll try to do in this
programme is to DEMONSTRATE them to you and to
show THAT THEY CAN BE SHAPED AND
CONTROLLED BY showing their effects RATHER
THAN the fields themselves.
VIDEO2 : MAGNETIC CIRCUITS (p77)
• This particular display of THE MAGNETIC FIELD OF A
PERMANENT MAGNET shows the field very clearly …
• …because the iron filings distribute themselves ALONG
THE DIRECTIONS OF THE LINES OF FORCE,
• …if that's the NORTH POLE and that's the South pole,
the LINES OF FORCE RUN FROM THE N POLE TO
THE S POLE
• … and the iron filings distribute themselves ALONG
these lines pointing TOWARDS the pole pieces of the
magnet. So in that particular instance the field is very
clearly demonstrated.
VIDEO3 : MAGNETIC CIRCUITS (p77)
• I can represent this with a diagram. HERE THERE IS A
DIAGRAM OF A PERMANENT MAGNET, N AT one
end and S. AT the other,
• …and the lines of force are running FROM THE N POLE
TO THE S POLE, roughly along the same pattern as
you saw in the iron filings demonstration.
• So, this is A SIMPLE GRAPHICAL REPRESENTATION
of the kind of thing that happens with a permanent
magnet.
VIDEO 4: MAGNETIC CIRCUITS (p77-78)
• Now, let's put two permanent
magnets side BY side. THIS IS THE
DISTRIBUTION OF LINES OF
FORCE THAT you get. They're
squeezed together BETWEEN these
two magnets, when the N is NEXT
TO N, and S. is NEXT TO S. What
does this actually mean IN
PRACTICE?
VIDEO 5: MAGNETIC CIRCUITS (p77-78)
• I can show this with some actual permanent magnets
that I have here, THEY ARE PERMANENT MAGNETS
MADE OF STEEL with N pole marked at each end so
that this resembles the diagram you just looked at. So if I
push the two together quite clearly ONE IS REPELLING
THE OTHER; if I press the two together side by side, it
is firmly pushed away. So, THERE IS A FORCE OF
REPULSION HERE. Let's go back to the diagram to see
how we might explain it.
• You see here the lines are apparently compressed and
they actually behave very much as though they are
ELASTIC AND COMPRESSIBLE so when lines of force
get compressed like that they do represent A FORCE
OF REPULSION shown here by these white arrows.
VIDEO 6 : MAGNETIC CIRCUITS (p78)
• If I TURN THE MAGNETS ROUND so that N is now
FACING S I'm sure you are very familiar with the fact they
attract ONE ANOTHER like this. This again can be shown
ON the diagram. Here the LINES OF FORCE now running
FROM N TO S are pulling the magnets together, there's A
FORCE OF ATTRACTION AS again shown by the arrows.
• The first main point I want to get over is that actually THESE
FIELDS CAN BE QUITE EASILY SHAPED BY USING
PIECES OF IRON to do this.
VIDEO 7 : MAGNETIC CIRCUITS (p78)
• Here I've got some pieces of iron. They ARE NOT
MAGNETIC at all, they DON'T ATTRACT EACH OTHER,
but if I put them along side these magnets like this, ALONG
one side so the two magnets face again, the two N poles
REPELLING, the two N poles OPPOSITE each other, so
they should repel EACH OTHER, what do you think will
happen?
• Let's see. NOTHING AT ALL. The FORCE OF REPULSION
has been almost completely removed. So, what happened is
that the MAGNETIC FIELD that was filling the gap
BETWEEN the magnets has been shunted away down the
iron; IRON IS A VERY MUCH MORE ATTRACTIVE route
for magnetic fields than does air; so it's been shunted away
and THE FORCE OF REPULSION IS REMOVED.
VIDEO 8 : MAGNETIC CIRCUITS (p78)
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Here you see the magnetic lines which were in the gap BETWEEN them as they
are still OUTSIDE the gap but now the lines have been shunted THROUGH the
iron represented BY this light grey area, shunted through there, LINES AGAIN
RUNNING FROM N TO S, in both magnets and the gap between them, you
see, has no lines of force left, SO THERE IS NO FORCE OF REPULSION LEFT
either.
Now I can demonstrate this effect rather more dramatically with a different pair of
magnets. Here I have a ferrite magnet. IT IS A MEGNETIC MATERIAL, ceramic
in nature and CAN BE MAGNETIZED quite strongly. Here you see there are two
rings, one ABOVE the other, the upper one is being supported BY THE
MAGNETIC FORCE exerted BY the lower one. All the magnetic forces interreact
to be more exact. This kind of levitation of a body DUE TO magnetic field will be
demonstrated in the next TV programme where the method is used to levitate a
train ABOVE the track.
But I can show you how the field can be shunted away FROM these two by
taking these pieces of iron again and slipping them between the magnets. As I
put them in, THE MAGNETIC FIELD IS GRADUALLY REMOVED until there
isn't any left and the upper magnet sinks DOWN onto the lower one, and
THERE IS NO FORCE OF REPULSION left; removing these pieces of iron
restores the levitation of the ring magnet.
TRANSLATION
• Some SCIENTISTS (WHO WERE) WORKING ON
ELECTROMAGNETISM
• could BE STRENGTHENED BY SENDING A CURRENT
THROUGH A COIL
• A GREATER/HIGHER NUMBER OF TURNS IN THE COIL
• AS IT ALSO DOES
• AROUND a piece of iron
• SINCE/AS THE IRON BECOMES MAGNETIZED
• DISCOVERY that A MAGNETIC FIELD COULD BE
CREATED BY AN ELECTRIC CURRENT
• AN EMF (ELECTROMOTIVE FORCE) IS CREATED
• THIS MAKES/CAUSES A CURRENT OF ELECTRONS Ø/TO
FLOW THROUGH THE WIRE
• for GENERATING
• LINES OF FORCE
• THE FASTER THE WIRE IS MADE TO TURN, THE
GREATER
TRANSLATION
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...placed BETWEEN ITS N &S poles
AS THE ROTOR TURNS
the wires in it CUT THE LINES OF FORCE
The rotor IS DRIVEN BY A TURBINE
produced BY BURNING COAL OR OIL
Transformers ARE ALSO BASED ON
ELECTROMAGNETISM,
They consist OF two COILS of wire WOUND
around pieces of iron
An ALTERNATING CURRENT FLOWS
THROUGH THE PRIMARY
MORE TURNS THAN THE SECONDARY
the secondary voltage INCREASES/GOES
UP/RISES.
INSTRUCTIONS
• The instruction itself (IMPERATIVE
or SHOULD)
• The result (PURPOSE) (What for?)
• The way of carrying out the
instructions (METHOD) (How?)
PURPOSE (WHAT FOR?)
• TO (NOT TO)
• SO AS TO (SO AS NOT TO) + INFINITIVE
• IN ORDER TO (IN ORDER NOT TO)
para+inf
FOR + NOUN = For more information, call…. This place is for exhibitions
• FOR THE PURPOSE OF
• WITH THE AIM OF
• WITH THE OBJECTIVE OF
+ GERUND
• SO THAT + SENTENCE
para que
(In order) to generate electricity, we need to use another form of
energy
Turn the lights off so as not to waste electricity
The new system raises the turbine’s condenser temperature so that all
the condensation energy can be used for district heating
METHOD (HOW?)
• BY
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+ VB -ING gerundio
BY
por, por medio de, mediante,…
BY MEANS OF
THROUGH
WITH
+ NOUN
WITH THE HELP/ASSISTANCE OF
Electricity is generated from water by using dams and by capturing the
potential energy of water
Generators produce electricity by means of a principle discovered in the early
1830's
Energy savings through improved mechanical systems
FOR
FOR = PREPOSITION (+ NOUN)
• indicating a goal: para, de, por
food for the party,
cure for cancer
to study for a test
for more information, call…
time for dinner , to travel for pleasure,
• indicating a recipient : para a gift for you
• indicating duration : por, durante he's going for two years
• indicating a particular time : para, por the wedding is
planned for April
enough for now
• indicating amount or value : por, de
a check for $100
FOR IS NOT USED TO INTRODUCE THE AGENT OF THE PASSIVE
POR
• Por causa de, debido a => because of, due to, owing to
I arrived late because of the traffic
• Por un lugar = by, along
I stopped by your house; along the coast
• durante ( tiempo) => for, during
they stayed there for a week
• por medio de => by means of
Voltage is changed by means of transformers
• a través de => through
Water flows through the pipes
• AGENT OF THE PASSIVE=> BY
The pyramids were built by the Egipcians
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PARA
PARA + NOUN
For somebody=> for
a present for you
For some purpose => for
the food is for the party what for?
indicating comparison => for
it's good for what it costs
Time => for, by, around
an appointment for Monday
it’ll be
ready by April
Direction => to, towards
they're heading towards the river to
the right/left
PARA + INFINITIVO (Purpose)
To, In order to, so as to + INFINITIVE
he does it to annoy you ; in order not to be seen too young to understand
PARA QUE+ SENTENCE
so that
Place the test tube so that it is below the water
INSTRUCTIONS
A F4: We start by winding the armature, the part of the motor that
moves. To make the armature nice and round, we wind it on a
cylindrical coil form, such as a small battery. Don't try to be neat, a
little randomness will help the bundle keep its shape better.
B F5: Now carefully pull the coil off of the form by holding the wire so
that it doesn't spring out of shape. To make the coil hold its shape
permanently, wrap each free end of the wire around the coil a
couple of times, making sure that the new binding turns are exactly
opposite each other, so as to allow the coil to turn easily on the axis
formed by the two free ends of wire, like a wheel.
C F2: Hold the coil at the edge of a table in order to keep it straight (not
flat on the table), with one of the free wire ends lying flat on the
table. With a sharp knife, remove the top half of the insulation from
the free wire end. Be careful to leave the bottom half of the wire with
the insulation intact. The top half of the wire will be shiny bare
copper, and the bottom half will be the color of the insulation. Do the
same thing to the other free wire end, making sure that the shiny
bare copper side is facing up on both wire ends
INSTRUCTIONS
D F·3: The next step is to make the axle supports. In order to make
the supports, take a stiff piece of bare wire (copper or brass will
work, as will a straightened paper clip) and bend it around a small
nail to make a loop in the middle. Do the same to another wire, so
you have two supports.
E F1: Attach the support wires securely to the battery holder by winding
the free ends several times through the small holes in the plastic at
each end. Bend the support wires so the rings are just far enough
apart for the armature to spin freely. Bend them apart a little and
insert the armature into both rings, then bend them back so that they
are close to the coil, but not touching it. Insert the battery into the
holder. Place the magnet on top of the battery holder just
underneath the coil.
• Note that there is a strip of paper stuck in between the battery and
the electrical contact in the holder. This is the on/off switch. Remove
the paper to allow electricity to flow into the motor, and replace the
paper in order to stop the motor.
LISTENING
1. THERMAL, LUMINOUS, CHEMICAL,
MAGNETIC
2. IT MAY HEAT THE CONDUCTOR
3. ELECTRIC MOTORS AND GENERATORS
4. NO. EG. DOMESTIC APPLIANCES
(ELECTRIC COOKERS) AND MANY
INDUSTRIAL PROCESSES
5. LIGHT
6. THE CONDUCTOR BECOMES
INCANDESCENT
7. THE FILAMENT OF A LIGHT BULB
8. WHEN A CURRENT IONIZES A GAS
9. GREENISH-BLUE LIGHT
LISTENING
10.
AN ELECTRIC CURRENT CAN SEPARATE A CHEMICAL
COMPOUND INTO ITS COMPONENTS
11.
BY ELECTROLYSIS OF SALT WATER
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TO BREAK DOWN WATER INTO HYDROGEN AND OXYGEN
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SULPHURIC ACID BECAUSE PURE WATER DOES NOT
CONDUCT WELL
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A MAGNETIC FIELD AROUND IT
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1-MAGNETIZE MAGNETIC MATERIALS AND ATTRACT THEM
TO THE CONDUCTOR (e.g. = RELAYS)
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2- IF THE MAGNETIC FIELD IS CUT BY ANOTHER
CONDUCTOR, AN ElectroMotiveForce WILL BE INDUCED IN
THAT CONDUCTOR (e.g.= TRANSFORMERS AND
GENERATORS)
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3-IF A CURRENT-CARRYING CONDUCTOR IS PLACED IN
THE MAGNETIC FIELD, A FORCE WILL BE EXERTED ON IT
(e.g.= MOTORS)