15. Use the information from the text to complete the tables and answer the questions.
Complete this table
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Sensing device |
Used to detect |
|
LDR |
|
|
|
heat |
|
|
sound |
What effect does light have on an LDR?
What is the purpose of RV1 in Fig. 2 ?
Use words from the text to complete the following table
|
Term |
Opposite |
|
cut-off |
saturation |
|
fixed resistor |
|
|
increases |
|
|
energize |
|
|
slow |
|
|
to cause |
|
|
forward bias |
|
How is the transistor in Fig. 2 protected from a large back EMF?
16. Study this simple circuit and answer the questions below it.
What are the components?
How are they connected?
What is the state of the system when the door is closed?
What happens if the door is opened?
Why does this happen?
Writing.
16. Write the text explaining how the door-alarm circuit works.
17. Write the translation of the paragraphs beginning with “The ldr forms the potential divider… “ and the next one.
Language Study. Grammar links
Sentences in all texts are held together by grammar links. Note the links in this paragraph about metal detectors.
(1) Metal detectors are used to locate hidden metal objects such as water pipes. (2) They contain a search coil and a control box. (3) The coil is mounted in the search head. (4) When an AC voltage from the box is applied to the coil, a magnetic field is created around it. (5) In turn this induces a current in any metal object the head passes over.
This paragraph illustrates some common grammar links:
Nouns become pronouns:
Metal detectors (1) becomes they (2).
Repeated nouns change from a to the and sometimes words are dropped:
A search coil (2) becomes the coil (3).
Clause and even sentences become this or that:
A magnetic field created around it (4) becomes this (5).
17. What words or word combinations in the text “Alarms and alarm systems” do these grammar links refer to?
1. … to eliminate it. (para 1)
2. The primary use of these clocks … (para 2)
3. … and its contents. (para 4)
4. … such as earthquakes or tornadoes. (para 5)
5. … that provides sensor power… (para 6)
6. … which a person may use … (para 9)
18. Find the words in bold in the text “Three stages of a simple alarm system” and write out the words or phrases they refer to.
lesson 11. The internet
Lead-in.
1. Answer the questions in pairs.
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1.How often do you surf the Internet?
2.What do you usually do on the Internet?
3.What are your favorite websites? What sites don’t you like? Why?
4. Have you ever designed your website?
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Reading and Vocabulary.
2. You are going to read the text about the Internet. Make sure you know these words and expressions.
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worldwide to link to carry path to stay in touch with to knock out to route to treat as initial definite merger |
commonplace quarter of Earth’s population message delay satellite to reshape instant retail outlet artisans and traders supply chain entire |
3.Read the information about the Internet and match the headings (A – F) and the paragraphs (1 – 5). There is one extra heading which you don’t need to use.
A. The Stages of Development of the Internet
B. Common Information
C. The Use of the Internet
D. The Internet services
E. The future of he Internet
F. Terminology
The Internet
1. The Internet is a global system of interconnected computer networks to serve billions of users worldwide. It consists of millions of private, public, academic, business, and government networks which are linked by a broad array of electronic, wireless and optical networking technologies. The Internet carries a vast range of information resources and services. Information sent over the Internet takes the shortest path available from one computer to another. Because of this, any computers on the Internet will be able to stay in touch with each other. If some computers on the network are knocked out, information will just route around them.
2. ‘Internet’ is a short form of the technical term ‘internetwork’, the result of interconnecting computer networks with special gateways or routers. The Internet is also often referred to as ‘the Net’. The term ‘the Internet’ is treated as a proper noun and written with an initial capital letter and the definite article. In the media and popular culture there is a trend to treat it as a generic term or common noun and thus write it as "the internet", without capitalization. Some people think that the word should be capitalized as a noun but not capitalized as an adjective.
3. The origins of the Internet reach back to research of the 1960s when the United States had private military interests to build distributed computer networks. The opening of the network to commercial interest began in the 1980s. It led to worldwide participation in the development of new networking technologies, and the merger of a lot of networks. In the 1990s an international network resulted in its popularization and incorporation into virtually every aspect of modern human life. By 1996 usage of the word ‘Internet’ had become commonplace. Nowadays more than a quarter of Earth's population uses the services of the Internet.
4. The most popular Internet service is e-mail (electronic mail). The most of the people, who have access to the Internet, use the Network only for sending and receiving e-mail messages. However, other popular services are available on the Internet: reading Usenet News, using the World Wide Web, Telnet, FTP, IRC, ICQ and Gopher. Most computer-mediated communication (CMC) is asynchronous. The participants are not on line at the same time and there are delays between messages. The examples of asynchronous communication are mobile phone messages, chat rooms and e-mail. Synchronous CMC depends on participants being on line at the same time. There may be a few seconds delay – like a satellite phone. The examples of synchronous communication are Internet Relay Chat, audio and video conferencing.
5. Most traditional communications media including telephone, music, film, and television are reshaped by the Internet, giving birth to new services. Newspaper, book and other print publishing are adapting to Web site technology, or are reshaped into blogging and web feeds. The Internet enables or accelerates new forms of human communication through instant messaging, Internet forums, and social networking. Online shopping booms both for major retail outlets and small artisans and traders. Business and financial services on the Internet affect supply chains across entire industries.