Transcript UNIT 2 CLASSIFICATION
UNIT 6 ELECTRICITY
• • • • • • •
Vocabulary
Ways of generating electricity Magnetism & Electromagnetism Generators and transformers
Grammar & Functions
Revision of connectors Prepositions Instructions: purpose and method Integrated practice of grammar and functions
• • • • • • • • • • • • • • • •
LISTENING: electricity
Electricity is a phenomenon of
SOME CHARGED SUBATOMIC PARTICLES
called
electrons
WHEN THEY START MOVING FROM ATOM TO ATOM
An atom is the smallest particle
OF WHICH ALL MATTER IS COMPOSED.
All atoms consist
of
a nucleus
CONTAINING PROTONS AND NEUTRONS, AROUND WHICH ELECTRONS ORBIT;
electrons orbiting farther from the nucleus
ARE MORE EASILY DRAWN AWAY
therefore are more likely to move and
CREATE AN ELECTRIC CURRENT
thus ,
AN ELECTRON IS NEGATIVELY CHARGED
whereas a proton is positively charged and
NEUTRONS HAVE NO ELECTRICAL CHARGE
an atom is electrically neutral
AS ONE ATOM. THERE ARE AS MANY PROTONS AS ELECTRONS IN
However
NUMBER
atoms of different substances
DIFFER FROM OF ELECTRONS AND PROTONS EACH OTHER
that they contain
. DEPENDING ON THE 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 An electron,
ON THE OTHER HAND ,
weighs only about
1/1800 (one eighteen hundredth) OF THE WEIGHT OF A PROTON OR NEUTRON
Yet to produce the movement of electrons
A DIFFERENCE IN POINTS
must be created
.
POTENTIAL BETWEEN TWO
Electric sources
SUCH AS BATTERIES, CELLS, GENERATORS, etc
change chemical, mechanical or other types of energy
INTO ELECTRICAL ENERGY
CONNECTORS
1.
2.
3.
WHEREAS / WHILE INSTEAD OF DUE TO THE FACT THAT / SINCE / AS 4.
5.
6.
7.
8.
THUS / THEREFORE DUE TO IN SPITE OF / DESPITE SINCE / DUE TO THE FACT THAT / AS ALTHOUGH / IN SPITE OF – DESPITE THE FACT THAT 9.
UNLIKE 10. WHICH 11. AS 12. DUE TO 13. THUS 14. ALTHOUGH ... THUS (THEREFORE).... INSTEAD 15. THAT
• • • • • • • • • • • •
NOUNS
ADD ition DIRECT ion STRONG/ strength DEVELOP ment ABLE/ ability ATTRACT ion SCIENCE/ scientist GENERATE/ or tion MAGNET ism REPEL/ repulsion DISCOVER y TRANSFORM er / ation
ELECTROMAGNETS
http://www.youtube.com/watch?v=EjfEiEwpuT8 • 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
wrapped
around
a coil (e.g. cardboard) a current
around
• 6- I get a North
at
one end and a South
at
travels
through
it • 7- I get no magnet the other
as
a wire the current • 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 drop it
in
the center some iron it will make it much stronger (10 20 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
1.
2.
3.
4.
5.
PREPOSITIONS
… when brought
NEAR
a magnet … attracted
BY
a magnet are capable
OF
becoming magnetized 6.
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
molecules
IN
matter individual The protons are basically trapped
INSIDE
the nucleus … Therefore, it is moving electrons….responsible
FOR
electricity.
7.
8.
9.
10.
11.
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 INSIDE
the magnet from the south pole
TO
surrounding …. … travel the north pole Originally … were thought of
AS
two separate forces.
… flowing
THROUGH
depending
ON
that
OF
a wire …magnetic field
AROUND
the current. the wire, its direction Some …technologies result
IN
the creation of solid waste 12.
13. A generator ..... energy
INTO
electrical energy. The process is based
ON
the relationship
BETWEEN
magnetism and electricity 14. 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, used a copper wheel and a horseshoe magnet.
IN which he The wheel was located BETWEEN the poles OF the magnet.
Electrical contacts were applied and AT the edge of it.
TO the wheel, both AT the centre These parts were connected TO an ammeter order to detect the electrical current.
BY means of wires IN Whenever the wheel rotated BETWEEN electrical current was shown ON / IN the ends of the magnet, an the ammeter ´s display.
When the wheel was made to turn needle too.
OF IN the opposite direction, the the ammeter was deflected IN the opposite direction, Therefore, according current depended TO ON this experiment, the direction of the 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 these lines pointing
TOWARDS ALONG
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 you saw in the iron filings demonstration. pattern
as
• 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)
Here you see the magnetic lines which were
in
the gap
BETWEEN
them
as
they are still
OUTSIDE
iron represented the gap but now the lines have been shunted
BY
this light grey area, shunted
through THROUGH
the 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
taking these pieces of iron again and slipping them
between
these two
by
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 ELECTROMAGNETISM could BE STRENGTHENED THROUGH A COIL BY ON SENDING A CURRENT 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 FLOW THROUGH A CURRENT OF ELECTRONS THE WIRE Ø/TO for GENERATING LINES OF FORCE THE FASTER THE WIRE IS MADE TO TURN, THE GREATER
TRANSLATION
• • • • • • • • • •
...
placed BETWEEN ITS N &S poles AS THE ROTOR TURNS the wires in it CUT THE LINES OF FORCE The rotor IS DRIVEN BY produced BY A TURBINE BURNING COAL OR OIL Transformers ARE ALSO BASED ON ELECTROMAGNETISM, They consist OF around two COILS of wire WOUND 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
T
urn 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
•
BY
METHOD (HOW?)
+ VB -ING
gerundio
• • • • •
BY BY MEANS OF
por, por medio de
THROUGH WITH
+ NOUN
WITH THE HELP/ASSISTANCE OF
,
mediante ,… Electricity is generated from water
by using
dams and
by capturing
potential energy of water the 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 for more information, call
…
to study for a test time for dinner , to travel for pleasure,
indicating a recipient : para
a gift for you
indicating duration : indicating a particular time :
planned for April
por , durante para
enough for now
,
he's going for two years
por
the wedding is
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
PARA
PARA + NOUN
For somebody
=>
for For some purpose
=>
a present for you
for
the food is for the party what for?
indicating
Time
=>
comparison
=>
for for, by, around
it's good for what it costs an appointment for Monday it’ll be ready by April
Direction
=>
to, towards
the right/left they're heading towards the river to
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 that the coil off of the form it doesn't spring out of shape. To make by holding the coil hold the wire so its shape permanently, opposite wrap each free end of the wire each other, so as to around the coil a couple of times, making sure that the new binding turns are exactly allow the coil to turn easily on the axis formed by the two free ends of wire, like a wheel.
C F2
: Hold flat on the coil at the table), the edge of a table with in order to keep it straight (not one of the free wire ends lying flat on the table. With a sharp knife, remove the free wire end. Be careful the top half of the insulation from 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. the supports, take In order to make a stiff piece of bare wire (copper or brass will work, as will a straightened paper clip) and bend nail to make a loop in the middle. Do the same it around a small 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 each end. Bend through the small holes in the plastic at the support wires so the rings are just far enough apart for the armature to spin insert the armature into freely. Bend both rings, then them apart a little and bend them back so that they are close to the coil, but not touching it. holder. Place the magnet on Insert the battery top of the battery holder just into the underneath the coil.
• Note that there is a strip of paper stuck in the electrical contact in between the battery and the holder. This is the on/off switch. Remove the paper to allow paper in order to electricity to flow stop the motor. into the motor, and replace the
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
10.
11.
12.
13.
14.
LISTENING
AN ELECTRIC CURRENT CAN SEPARATE A CHEMICAL COMPOUND INTO ITS COMPONENTS BY ELECTROLYSIS OF SALT WATER TO BREAK DOWN WATER INTO HYDROGEN AND OXYGEN SULPHURIC ACID BECAUSE PURE WATER DOES NOT CONDUCT WELL A MAGNETIC FIELD AROUND IT 15.
16.
17.
1-MAGNETIZE MAGNETIC MATERIALS AND ATTRACT THEM TO THE CONDUCTOR (e.g. = RELAYS) 2- IF THE MAGNETIC FIELD IS CUT BY ANOTHER CONDUCTOR, AN ElectroMotiveForce WILL BE INDUCED IN THAT CONDUCTOR (e.g.= TRANSFORMERS AND GENERATORS) 3-IF A CURRENT-CARRYING CONDUCTOR IS PLACED IN THE MAGNETIC FIELD, A FORCE WILL BE EXERTED ON IT (e.g.= MOTORS )
HOMEWORK
SECTION II ESSAY 3 ELECTRICITY & ENERGY (250 words) INCLUDE & UNDERLINE
• •
12 Grammar expressions from the list Word Formation (10 Nouns & 6 Adj) DEADLINE :
19 th MAY