Характеризування предметів

Описуючи предмети, ми використовуємо різні прикметники та прислівники або інші слова, що виконують їх роль. Подивимось, для прикладу, як ми можемо охарактеризувати новий комп’ютер та його роботу:

I’ve got a new modern computer. It works fast and effectively. It is equipped with all the necessary peripheral devices that allow me to use it for my work as well as for entertainment. It has two high speed processors that perform more than 10 billion operations per second. Its casing made of wood and metal looks great and attracts the sight of anyone who comes into my room.

Для отримання інформації про предмет ми використовуємо різні типи спеціальних питань, що починаються словами how (big, long, fast …), what/which (colour, weight …), who, whose і т. д.

Exercise 1. Play a guessing game. Ask your classmate as many questions as possible to get information about an object or a phenomenon.

Вправи для самостійної роботи

Exercise 1. Translate the text into Ukrainian (Russian).

When objects are connected in series, the electric current flows through them against the resistance of the first object, then against the resistance of the next object, and so on. Therefore the total resistance to the current is equal to the sum of the individual resistances. If three objects with resistances R₁, R₂, and R₃ are connected in series, their total resistance is R₁ + R₂ + R₃. For example, if a motor with a resistance of 48 ohms is connected to the terminals of a current source by two wires, each with a resistance of 1 ohm, the total resistance of the motor and wires is 48 + 1 + 1 = 50 ohms. If the voltage is 100 volts, a current of 100/50 = 2 amp will flow through the circuit.

Voltage can be thought of as being used up by the objects in a circuit. The voltage that each object uses up is called the voltage drop across that object. Voltage drop can be calculated from the equation V = IR, where V is the voltage drop across the object, I is the amount of current, and R is the resistance of the object.

In the example of the motor, the voltage drop in each wire is V = IR = 2 × 1 = 2 volts, and the voltage drop in the motor is 2 × 48 = 96 volts. Adding up the voltage drops (2 + 2 + 96) gives a total drop of 100 volts. If various objects are connected to form separate paths between the terminals of a source of electric current, they are said to be connected in parallel.

The total resistance of objects connected in parallel is less than that of any of the individual resistances. This is because a parallel circuit offers more than one branch (path) for the electric current, whereas a series circuit has only one path for all the current.

The electric current through a parallel circuit is distributed among the branches according to the resistances of the branches. If each branch has the same resistance, then the current in each will be equal. If the branches have different resistances, the current in each branch can be determined from the equation I = V/R, where I is the amount of current in the branch, V is the voltage, and R is the resistance.

The greater the resistance of a given branch, the smaller the portion of the electric current flowing through that branch. If a parallel circuit of three branches, with resistances of 10, 15, and 30 ohms, is connected to a 150-volt source, the branch with a resistance of 10 ohms would receive a current of V/R = 150/10 = 15 amp.

Exercise 2. Pretend that you are a master in electricity and you are going to show the ropes for some beginners in an office. Make notes about safe treating common office and household electrical instruments.

Exercise 3. Use the proper forms of the verbs (perfect or perfect continuous):

1) Look! Somebody ________ (steel) my purse.

2) I ___________ preparing letters for our clients. I ___________ (finish) four of them and there are two more to write.

3) I ________ (read) the thesis you gave me to check but I still _______ (not/finish) them yet.

4) My friend is a writer, he _____________ several books and plays.

5) When are you going to come? I _________ (already/wait) for an hour.

Lesson 5

Date: 2016-06-09; view: 427; Нарушение авторских прав