Basic HTML Version
1
Verbs (v.)
bind/bound stick/stuck deflect zip around detach
Adjectives (adj.)
loose
Nouns (n.)
path beam
Electrons in Motion
9
Brainstorming
Before reading Text 2, match these words with the definitions below.
Use a dictionary if you need to.
a
.............................................
:
fix, glue, tie; attach in some way one thing to another; fasten something
tightly; combine with through chemical bonding.
b
.............................................
:
turn aside from a straight course.
c
.............................................
:
a ray or shaft of light – a directional flow of particles.
d
.............................................
:
not firmly or tightly fixed in a place.
e
.............................................
:
a way or a track designed for a particular purpose.
f
.............................................
:
move rapidly.
g
.............................................
:
fix something on.
h
.............................................
:
separate.
10
Skim the text to understand its global meaning and answer the question posed by the title.
11
Classwork
Now scan the passage and write your definition of free electrons and of mass of an
electron. Compare your definition with your classmates.
TEXT 2
How do electrons become free?
I
f electrons are the normal constituents
of atoms, how can they become free? To
answer this question you must consider how
atoms are structured.
Atoms, you know, are extremely small,
with a nucleus at their core and electrons
orbiting around it.
In many materials, the electrons are tightly
bound
1
to the atoms. Wood, glass, plastic,
ceramic, air, cotton are electrical
insulators because their electrons don’t
move but remain stuck
2
to their atoms.
Most metals, however, have electrons
that can
detach
from their atoms and zip
around
3
. These are called free electrons.
These loose electrons make it easy
for electricity to flow through these
materials, so they’re known as electrical
conductors. They conduct electricity.
The moving electrons transmit electrical
energy from one point to another. From
the point of view of electronics, the two
most important properties of an electron
are its electrical charge and its small
mass. Most of the mass of an atom lies
in the nucleus. In fact, the neutron and
proton have about equal masses whereas the
mass of an electron is about 2,000 times
smaller than either particle.
Its small mass means that the path of a
beam of electrons
can easily be
deflected
by electric and magnetic fields or by
small voltages.
1
bound
: linked to, tied or attached to
2
stuck
: firmly attached to, difficult
to remove, blocked
3
zip around
: move around very fast
beam of electrons
fascio di elettroni
(to) deflect
deviare
(to) detach
separare
TECHNICAL ENGLISH
Progetto FOR ELECTRONICS_unit_1.indd 11
10/01/