Lesson 6.
Topic “Electric circuit”
Grammar material: Comparisons.
Text: “ Electric circuit”
The electric circuit is the subject to be dealt with in the present article. But what does the
above term really mean? We know the circuit to be a complete path which carries the
current from the source of supply to the load and .then carries it again from the load back
to the source.
The purpose of the electrical source is to produce the necessary electromotive force
required for the flow of current through the circuit.
The path along which the electrons travel must be complete otherwise no electric power
can be supplied from the source to the load. Thus we close the circuit when we switch on
our electric lamp.
If the circuit is broken or, as we generally say “opened” anywhere, the current is known to
stop everywhere. Hence, we break the circuit when we switch off our electrical devices.
Generally speaking, the current may pass through solid conductors, liquids, gases,
vacuum, or any combination of these. It may flow in turn over transmission lines from the
power-stations through transformers, cables and switches, through lamps, heaters, motors
and so on.
There are various kinds of electric circuits such as: open circuits, closed circuits, series
circuits, parallel circuits and short circuits.
To understand the difference between the following circuit connections is not difficult at
all. When electrical devices are connected so that the current flows from one device to
another, they are said to be connected in series. Under such conditions the current flow is
the same in all parts of the circuit, as there is only a single path along which it may flow.
The electrical bell circuit is considered to be typical example of a series circuit. The
parallel circuit provides two or more paths for the passage of current. The circuit is divided
in such a way that part of the current flows through one path, and part through another.
The lamps in your room and your house are generally connected in parallel.
Now we shall turn our attention to the short circuit sometimes called "the short" The short
circuit is produced when the current is allowed to return to the source of supply without
control and without doing the work that we want it to do. The short circuit often results
from cable fault or wire fault. Under certain conditions, the short may cause.
Test: Electric circuit
I. Fill in the blanks with the words and phrases:
Complete, fuse, open circuit, supplied, transmission line, fault, closed circuit,
conductor, load, switch, safety device, short circuit, carry, cables.
1. The current does not flow if there is an ……
2. A fuse is a ……
3. Our laboratory is …… with electrical materials.
4. A new high voltage …… was put into operation in Siberia.
5. We tested the new …… in the high voltage laboratory.
6. The current flows when there is a ……
7. Copper is the best …… of electricity.
8. The …… of the electrical system was caused by lightning.
9. The ability to …… electrical charges is known as conduction.
10. This circuit consists of some …… paths.
11. A …… placed in a electrical circuit serves as a means of protection.
12. The …… of the power-stations often varies.
13. A …… is dangerous as it sometimes causes.
14. A …… is used to break the circuit.
II. Connect the word combinations:
electric
path
various
device
single
kinds
safety
circuit
carrying
capacity
III. Find the end of the sentences:
1. The circuit is …
2 .The purpose of the electric circuit is…
3. When we switch off our electric devices, …
4. The current may pass through …
5. There are various kinds of electric circuits, such as…
6. The lamps in your room and your house are generally connected…
7. The short circuit is produced…
8.The fuse …
1.open circuits, closed circuits, series circuits, parallel circuits
and short circuits.
2.must be placed in every circuit, where there is a danger of
overloading the line.
3.complete path which carries the current from the source of
supply to the load and then carries it again from the load
back to the source.
4.we break the circuit.
5.when the current is allowed to return to the source of
supply without control and without doing the work that we
want it to do.
6.solid conductors, liquids, gases, vacuum.
7.in parallel.
8.to produce the necessary electromotive force.
Grammar.
I. Complete the following sentences by filling in the blanks with the superlative forms
of the irregular adjectives shown in brackets.
1. This is the ____________ we have ever traveled in one day. (far)
2. Their farm has produced the _____________ tomatoes. (many)
3. Our strawberries have the _____________ flavor. (good)
4. He ate the _____________ jam. (little)
5. That is the _____________ news I have heard yet. (bad)
6. She has the ______________ cheese. (much)
7. They have eaten the _____________ pancakes. (many)
8. That is the ____________ thing that could happen. (bad)
9. We have used the _____________ honey. (much)
10. That is the _____________ suggestion we have heard yet. (good)
11. This is the _____________ stretch of road. (bad)
12. They produced the _____________ butter this year. (little)
II .Rewrite each of the following sentences, changing the positive form of the
adjective to the superlative form, and using the definite article the. Use the words
given in brackets as the second part of the comparison. For example:
This is a cold room. (in the house)
This is the coldest room in the house.
That is a good example. (he could find)
That is the best example he could find.
1. This is an old house. (on the street)
2. That is a large store. (in the city)
3. This is a cool evening. (we have had this week)
4. He is a kind man. (I know)
5. This is a fine view. (in the area)
6. That is a new building. (in town)
7. This is a dusty road. (I have ever walked along)
8. That was a bad storm. (we have had for ten years)
9. This is a long river. (in the country)
10. That is a funny story. (you have ever told)