Professional Literacy Development - Electricity
Did you know?
 Long before any knowledge of electricity existed, people were aware of
shocks from electric fish.
 Thales of Miletos, a Greek philosopher, made a series of observations on
static electricity around 600 BC.
 Electricity remained relatively unknown until 1600, when the English scientist William Gilbert
made a careful study about it, using amber (SLO: jantar). He then coined the New Latin word
electricus, meaning "like amber".
 The English word “electricity” was first used in 1646.
 The first use of water to generate electricity was in 1882 in the Austro-Hungarian Empire. It
produced enough power to light the Emperor’s summer residence.
Task 1 Scan the text and find the information missing from the table.
Slovene
1. električna upornost, R
English
Symbol
SI Unit
2. električni naboj, Q
3. napetost, U
4. specifična električna
upornost, ρ
5. električni tok, I
Electricity
1. ELECTRICITY is a physical phenomenon associated with the flow of electric
charge (Q). Electric charge is a fundamental property of matter. Its SI unit is
the coulomb, C. Charge originates in the atom, in which its most familiar
carriers are the electron and proton. Electrons are negatively charged and
protons positively charged. Each has one unit charge, but of opposite sign.
2. Electricity can flow only if there is a complete circuit from the battery
through wires to components and back to the battery again. The diagram (on the
right) shows a simple circuit of a battery, wires, a switch and a lamp. With the switch
open, the circuit is broken - so electricity cannot flow and the lamp is off. With the
switch closed, the circuit is complete - allowing electricity to flow and the lamp is on.
3. Electric current (I) is the rate of charge flow past a given point in an electric circuit,
measured in coulombs/second or amperes, A. It is measured with an ammeter. We
say “current through a component”.
4. Voltage (V) is a measure of the energy carried by the charge. Strictly speaking, it is the
"energy per unit charge". It is measured in volts, V (joules per coulomb). It is
measured with a voltmeter. The proper name for voltage is potential difference or p.d. for short, but this term
is rarely used in electronics. Voltage is supplied by a battery or power supply. It is used up in components, but
not in wires. We say “voltage across a component”.
5. A conductor is a material through which electric current can flow freely. Metals such as copper are good
examples of conductors, while most non-metallic solids are said to be good insulators, having extremely high
resistance to the flow of charge through them. "Conductor" implies that the outer electrons of the atoms are
loosely bound and free to move through the material. Simply stated, most metals are good electrical
conductors, and most non-metals are not.
6. In most materials other than metals, even the outermost electrons are so tightly bound that there is
essentially zero electron flow through them with ordinary voltages. This is the mark of a good insulator.
Insulators are commonly used as a flexible coating on electric wiring and cabling.
7. The electrical resistance (R) of an electrical element is the opposition to the passage of an electric current
through that element. It is given by the equation R = V/I and is measured in ohms (Ω). According to Ohm’s law,
for many conductors of electricity, the electric current which will flow through them is directly proportional to
the voltage applied to them.
8. The electrical resistance of a wire would be expected to be greater
for a longer wire, less for a wire of larger cross sectional area, and
would be expected to depend upon the material out of which the
wire is made. The resistance of a wire can therefore be expressed
as (see right):
9. Electrical resistivity is a property of a material. It expresses how
strongly the material opposes the flow of electric current. A low
resistivity indicates a material that readily allows the movement
of electric charge. The SI unit of electrical resistivity is the
ohm⋅metre (Ω⋅m). It is commonly represented by the Greek letter
ρ (rho).
Task 2 Indicate whether the statements are true or false according to the text. Correct the false statements to
make them true.
a) Electrons and protons are charged carriers in an atom.
b) Electrons are positively charged.
c) A complete circuit allows electricity to flow through its components.
d) When a switch is closed, the circuit to which it belongs is said to be broken.
e) Current is measured with an ammeter.
f)
“Volts” is equivalent to “Joules per coulomb”.
g) The proper name for current is potential difference.
h) Outer electrons in a conductor are tightly bound to each other.
i)
Insulators are used as a flexible coating on electric wiring and cabling.
j)
Resistivity expresses how strongly a material opposes the flow of electric current.
Task 3 Find words from the text that correspond to the definitions.
1. a negatively charged carrier found in atoms (para 1) ______________________
2. a positively charged carrier found in atoms (para 1) ______________________
3. the complete path of wires and equipment along which electricity flows (para 2) ______________________
4. a small device that you press or move up and down in order to turn a piece of electrical equipment on and off
(para 2) ______________________
5. materials that do not let electrons flow easily through them (para 5) ______________________
6. materials through which electrons can flow freely (para 5) ______________________
7. furthest from the inside or centre (para 6) ______________________
8. a thin layer of a substance covering a surface (para 6) ______________________
9. a statement showing that two amounts or values are equal (para 7) ______________________
10. a quality or characteristic that something has (para 9) ______________________
Task 4 Complete these sentences with appropriate prepositions from the text.
1. Electricity is usually associated ___________ the flow of electric charge. (para 1)
2. Charge originates ___________ the atom. (para 1)
3. Electric current (I) is the rate of charge flow ___________ a given point in an electric circuit. (para 3)
4. Electric current ___________ a component is measured ___________ amperes, A. (para 3)
5. Voltage ___________ a component is measured ___________ a voltmeter. (para 4)
6. The resistance (R) of an element is given ___________ R = V/I. (para 7)
7. According to Ohm’s law, electric current is directly proportional ___________ voltage. (para 7)
8. The resistance (R) of a wire can be expressed ___________ R = ρl/A. (para 8)