# Some Properties of Matter. Грекова О.А. - 18 стр.

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18
Unit 8
1. Check up the meaning of the following words:
Verbs:
commemorate, wind (wound, wound), connect, flow, find, found.
Nouns: significance, current, coil, wire, galvanometer, circuit, magnet, transformer, dynamos,
armature, voltage, essence.
Electromagnetic induction
In 1831 Faraday made a discovery that is of fundamental significance for electronic
theory and is also the basis of practically all electrical engineering. Its, in fact, so important
that in 1931 a great celebration was held in London to commemorate the discovery. The
essence of this discovery was that a magnetic force could produce a current.
Faradays experiment was carried out in the following way: on the iron ring were
wound two separate coils of insulated wire, one being connected to a galvanometer and the
other to a battery. There was a key in the battery circuit that could make and break the
electrical contact, so as to cause a current to flow or to make it cease flowing.
What Faraday found was that when a steady current was flowing in one coil, no
current flowed in the other coil, but that the breaking or making of the current in one coil gave
rise to a momentary current in the other coil. In this ring experiment the current makes an iron
ring a magnet.
The experiment shows that any change of the magnetic force passing through a coil
produces a current in that coil, as can also be demonstrated very simply with a coil connected
to a galvanometer. Increase of the magnetic force through a coil leads to a current in one
direction, decrease of force to a current in the other direction. This fundamental phenomenon is
called electromagnetic induction. Faradays iron ring is the simplest form of the modern
transformer, which transforms one alternating current into another alternating current of a
different voltage.
Modern dynamos, which are machines for producing large currents, are all founded
on this electromagnetic induction.
The rotating construction of iron surrounded by coils of wire is called the armature of
the dynamo. The more current that is being taken from the dynamo, the more mechanical
power is required to keep the armature turning. Nothing for nothing is the rule in physics.
Comprehension check:
1) When did Faraday make the discovery of the phenomenon of electromagnetic induction?
2) What was the essence of that discovery?
3) How was Faradays experiment carried out?
                                                18

Unit 8

1. Check up the meaning of the following words:
Verbs: commemorate, wind (wound, wound), connect, flow, find, found.
Nouns: significance, current, coil, wire, galvanometer, circuit, magnet, transformer, dynamos,
armature, voltage, essence.

Electromagnetic induction

In 1831 Faraday made a discovery that is of fundamental significance for electronic
theory and is also the basis of practically all electrical engineering. It’s, in fact, so important
that in 1931 a great celebration was held in London to commemorate the discovery. The
essence of this discovery was that a magnetic force could produce a current.
Faraday’s experiment was carried out in the following way: on the iron ring were
wound two separate coils of insulated wire, one being connected to a galvanometer and the
other to a battery. There was a key in the battery circuit that could make and break the
electrical contact, so as to cause a current to flow or to make it cease flowing.
What Faraday found was that when a steady current was flowing in one coil, no
current flowed in the other coil, but that the breaking or making of the current in one coil gave
rise to a momentary current in the other coil. In this ring experiment the current makes an iron
ring a magnet.
The experiment shows that any change of the magnetic force passing through a coil
produces a current in that coil, as can also be demonstrated very simply with a coil connected
to a galvanometer. Increase of the magnetic force through a coil leads to a current in one
direction, decrease of force to a current in the other direction. This fundamental phenomenon is
called electromagnetic induction. Faraday’s iron ring is the simplest form of the modern
transformer, which transforms one alternating current into another alternating current of a
different voltage.
Modern dynamos, which are machines for producing large currents, are all founded
on this electromagnetic induction.
The rotating construction of iron surrounded by coils of wire is called the armature of
the dynamo. The more current that is being taken from the dynamo, the more mechanical
power is required to keep the armature turning. Nothing for nothing is the rule in physics.

Comprehension check:

1) When did Faraday make the discovery of the phenomenon of electromagnetic induction?
2) What was the essence of that discovery?
3) How was Faraday’s experiment carried out?