Download The Force that Transformed the World In order to talk about

The Force that Transformed the World
In order to talk about electricity, it is necessary first to talk about the atom. The idea of
the ‘atom’ has a long history, one extending back to about 600 B.C. and the time of the
ancient Greeks. They believed that all matter was made up of atoms. The word ‘atom’
in fact comes from the Greek word ‘atomos’ which means ‘indivisible.’ It was not until
1897 that it was discovered that the atom is not indivisible but is composed of even
smaller particles. Among these particles one is called ‘the electron.’
Electrons orbit around the center or nucleus of the atom, much as the planets in
the solar system orbit around the sun. electrons closer to the nucleus are held more
tightly that those in the outer orbits. It is the electrons in the outermost orbit of certain
kinds of atoms that can be made to flow as electric current.
Electrons flow easily through certain kinds of materials called ‘conductors.’
Many metals, such as silver, copper, gold and aluminium are good conductors. Good
conductors are used in electric circuits to provide a path for the current.
Other substances provide strong resistance to the flow of current. These
substances are called ‘insulators,’ which are used to confine a current to the desired
path. Substances such as hard rubber, glass, wax and certain kinds of plastic are good
insulators. Thus, the cord on an electric appliance consists of a piece of wire, generally
copper, surrounded by a type of plastic or vinyl, the insulator confining the current to
its path.
The pressure that makes electrons flow along wires is called ‘voltage.’ Voltage
may be created by a generator at a power plant or by an electric battery. When you turn
on a light or an electric appliance, electrons are drawn from a generator at a power
plant. When you turn the light or appliance off, there will be electric pressure or voltage
built up at the switch, but no current will flow. It is somewhat similar to the way a water
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system works.
When you turn on a water faucet, water flows through the pipes, which is like
electric current flowing through wires. When you turn off a faucet, water pressure
remains but no water flows through the faucet. Similarly, when you turn off an electric
appliance, voltage remains, but no current flows. In a water system, the whole operation
depends on water pressure generated by a water pump. In an electric system, the
generator (or battery) creates the pressure called ‘voltage.’
Circle the correct number:
1. Electrons will flow easily through copper and silver because they are good
a. Particles
b. conductors c. regulators
d. insulators
2. Electrons are smaller particles of
a. Circuits
b. currents
c. voltage
d. atoms
3. One function of an insulators is to confine an electric current to its
a. Voltage
b. orbit
c. path
d. generator
4. Similar to the way that planets orbit around the sun, electrons in an atom orbit
around the
a. nucleus
b. generator
c. flow
d. voltage
5. A substance that offers strong resistance to the flow of electric current is called
a. A battery b. a conductor c. an appliance
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d. an insulator
6. Another term for electric pressure is
a. Current
b. voltage
c. faucet
d. switch
7. Rubber, glass and wax are good
a. Insulators
b. conductors c. regulators
d. generators
8. At a power plant, a generator is used to create voltage, which is the pressure that
makes
a. Atoms
b. circuits
c. electrons
d. orbits
Decide whether the following sentences are True (T) or False (F):
1. With a light turned off, no current will flow but there will be voltage at the
switch.
2. It was discovered in 1897 that the electron was made up of particles called
atoms.
3. An electric cord consists of wire surrounded by an insulator.
4. Electrons closer to the nucleus of an atom can easily be made to flow as electric
current.
5. Plastic or vinyl are often used as conductors.
6. Voltage can be created by a battery.
7. When a switch is turned on, voltage will prevent current from flowing.
8. The Greeks believed that all electricity was made of atoms and electrons.
9. Aluminium and gold can be used as conductors.
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In paragraph 1, the word idea could be replaced by:
a. Concept
b. Grist
c. Mould
d. Moth
e. Nothing of the above
In paragraph 1, the phrase was made up of could be replaced by:
a. Mortified
b. Officiated
c. Consisted of
d. Pinched
e. Nothing of the above
In paragraph 1, the phrase comes from is near the meaning of:
a. Evacuates
b. Sulks
c. Derives from
d. Plays about
e. Puts forward
f. Nothing of the above
In paragraph 2, the word certain is near the meaning of:
a. Punnet
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b. Punitive
c. Reptile
d. Reputable
e. Nothing of the above
f. All the above
In paragraph 3, the word provide is near the meaning of:
a. Supply
b. Scrub
c. Tabulate
d. Tallow
e. Nothing of the above
In paragraph 3, the word path could be replaced by:
a. Tipster
b. Lane
c. Rissole
d. Roach
In paragraph 4, the word substances could be replaced by:
a. materials
b. tabors
c. truncheons
d. niggards
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1. The doctors said that this medicine is _______ effective.
a. neither safe nor
b. neither safe and not
c. not either safe and
d. not either safe nor
2. “Can we walk to the park from here?”
“No, it _______ too long.”
a. is taking
b. would take
c. must be taking
d. should take
3. Professor Green has had a big impact _______ many of my students.
a. in
b. on
c. to
d. with
4. The author _______ signed my book.
a. her
b. herself
c. who
d. she
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