UNIT 9 - ELECTRIC CURRENT
electric current n. /i'lektrik 'kʌrәnt/ - a flow of electric charge through a conductor. It
is measured in amperes
source n. /'so:s/ - the point or place from which something originates
steady adj. /'stedi/ - continuous
phenomenon n. /fi'nominәn/ - anything that can be perceived as an occurrence
former adj. /'fo:mә/ - belonging to or occurring in an earlier time
charge n. /'t∫a:dʒ/ - amount of electricity stored in a battery
determine v. /di'tз:min/ - to ascertain or conclude
in addition to - besides; as well as
suppose v. /sә'pәuz/ - to presume (something) to be true without certain knowledge
flow v. /'flәu/ - to move or progress freely as if in a stream
circuit n. /'sз:kit/ - a complete path through which an electric current can flow
wire n. /'waiә/ - a flexible metallic conductor, esp one made of copper, usually
insulated, and used to carry electric current in a circuit
electron n. /i'lektrәn/ - a stable elementary particle present in all atoms
minute adj. /mai'nju:t/ - very small; diminutive; tiny
particle n. /'pa:tikәl/ - a body with finite mass that can be treated as having negligible
size, and internal structure
as conj. /æz/ - since; seeing that
through prep. /'θru:/ - starting at one side and coming out at the other side of
requirement n. /ri'kwaiәmәnt/ - a thing desired or needed
melt v. /'melt/ - to become or make liquid as a result of the action of heat
conduct v. /kәn'dʌkt/ - to transmit (heat, electricity, etc)
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electrolyte n. /i'lektrәu‚lait/ - a solution or molten substance that conducts electricity
direct current n. - a continuous electric current flowing in one direction only (DC, dc)
battery n. /'bætәri/ - two or more primary cells connected together to provide a
source of electric current
i.e. /ai i:/ (abbreviation for id est) - that is, that is to say; in other words; namely
terminal n. /'tз:minәl/ - a point at which current enters or leaves an electrical device,
such as a battery or a circuit
alternating current n. /'o:ltә‚neitiŋ 'kʌrәnt/ - a continuous electric current that
periodically reverses direction, usually sinusoidally (AC, ac)
power n. /'pauә/ - the rate at which electrical energy is fed into or taken from a
device or system. It is measured in watts
lighting n. /'laitiŋ/ - the act or quality of illumination
purpose n. /'pз:pәs/ - the reason for which anything is done, created, or exists
assume v. /ә'sju:m/ - suppose
cycle n. /'saikәl/ - a completed series of events that follows or is followed by another
series of similar events occurring in the same sequence
ampere n. /'æmpeә/ - the SI unit used to measure electric current, equal to a flow of
6.28×1018 electrons per second
volt n. /'vәult/ - the derived SI unit of electric potential (symbol V)
watt n. /'wot/ - the derived SI unit of power, equal to 1 joule per second (symbol W)
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NOTE:
 Heteronyms:
minute n. /'minit/ - a period of time equal to 60 seconds; one sixtieth of an hour
minute adj. /mai'nju:t/ - very small; diminutive; tiny
Malone changed his mind at the last minute.
You only need to use a minute amount of glue.
* Alessandro Giuseppe Antonio Anastasio Volta (1745 – 1827) was an Italian
physicist known for the invention of the battery in the 1800s.
* André-Marie Ampère (1775 –1836) was a French physicist and mathematician
who is generally regarded as one of the main founders of the science of classical
electromagnetism, which he referred to as "electrodynamics". The SI unit of
measurement of electric current, the ampere, is named after him.
EXERCISES:
A) Answer the questions.
1. Is there any difference between the electric current and static charge?
2. Who was the first to make a source of steady electric current?
3. Who distinguished the electric current from static charge?
4. Was Ampere right when he determined the direction of the current?
5. Define electron.
6. Can the electric current flow through gases?
7. What does DC stand for?
8. What kind of current is direct current?
9. What does AC stand for?
10. What’s the direction of the alternating current?
B) True or false.
1. Direct current is the unidirectional flow of electric charge.
2. Direct current is produced by sources such as batteries, thermocouples, solar
cells, and commutator-type electric machines of the dynamo type.
3. In alternating current the movement of electric charge periodically reverses
direction.
4. AC is the form in which electric power is delivered to businesses and residences.
5. Electric current is the same as static charge.
6. The unit of electric current is an ampere.
7. The unit of electric potential is a watt.
8. A volt is the unit of power.
9. Current can flow through solids, liquids and gases.
C) Fill in the blanks with the proper adjective in the correct form.
good little much great thin important
efficient
high far
early
1. Ohm's law is one of the ______________ laws in physics.
2. From the ______________ times people have dreamed of air flights.
3. Materials having free electrons are ______________ electric conductors.
4. The metals are the ______________ conductors of heat.
5. The electrons ______________ from the nucleus are loosely bound to the atom.
6. The thicker wire you use, the ______________ current will flow through it.
7. The ____________ wire you use, the ______________ current will flow through it.
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8. The greater the energy of the revolving electron, the ______________ from the
nucleus it will revolve.
9. The ______________ the voltage, the better should be the insulation.
10. The ______________ the difference between the temperatures, the
______________ the engine.
D) Match the terms and definitions.
1. electron
A) an electric current that flows in one direction steadily
2. charge
B) a flow of electric charge through a conductor
3. electrical energy
C) the SI unit used to measure electric current
4. current
D) a stable elementary particle present in all atoms
5. ampere
E) an electromotive force or potential difference expressed
in volts
6. AC
F) a complete path through which an electric current can
flow
7. atom
G) a continuous electric current that periodically reverses
direction
8. DC
H) the smallest quantity of an element that can take part in
a chemical reaction
9. circuit
I) the quantity of unbalanced electricity in a body (either
positive or negative)
10. voltage
J) energy made available by the flow of electric charge
through a conductor
E) Make passive.
1. Volta first produced a source of steady continuous current.
2. Scientists were forming theories on the subject.
3. They could see no real difference.
4. Men of science named the unit of current after famous French scientist
Ampere.
5. Ampere determined the difference between the current and the static charge.
6. We now know that the current flows from the negative pole of the source to the
positive pole.
7. We consider the electron to be a stable elementary particle present in all
atoms.
8. We also know that an electric charge of the electron to be negative.
9. People say that the wire conducts an electric current.
10. The electric current produces some most important effects to meet industrial
requirements.
11. The battery is pushing the electrons in the same direction all the time.
12. We know that AC flows first in one direction and then in the opposite one.
13. We assume that AC used for power and lighting goes through 50 cycles in a
second.
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