Контрольная работа №5 (5)
I. Прочитайте весь текст, а затем письменно переведите 1, 3, 4 абзац текста. Английский текст перепишите на левой странице тетради, русский перевод - на правой:
1. When a wire carrying a current is surrounded by a magnetic field, the force acting on the wire is proportional to the current as well as to the strength of the field. One should take advantage of this fact to measure currents.
2. The ampermeter is the instrument that is generally used for measuring the current flowing in an electric circuit, the electricians having abbreviated the name "ampermeter" to ammeter.
3. The best ammeters for d. c. for measurements are the ammeters of the magneto-electric system. They are quite similar in design to d. c. motors, only more delicate. In an ammeter an armature coil rotates between the poles of a permanent magnet, but the coil restrained by a spring is able to turn but through a small angle. The greater the current in the coil, the greater the force, and, therefore, the greater the angle of rotation of the armature. The deflection is measured by means of a pointer attached to the armature, the scale under the pointer reading directly in amperes.
4. When the currents to be detected and measured are very small, one should use a galvanometer. A galvanometer is a sensitive instrument used to detect and measure small electrical currents. Some very sensitive galvanometers are reported to detect a current as small as 10 -11 of an ampere per 1 mm of the scale.
5. A voltmeter is an instrument to be used for measuring the potential difference between the two points in a circuit. Its action is similar to that of an ammeter, both of them having armatures that move when an electric current is sent through their coils.
6. The deflection is proportional to the current flowing through the armature coil.
II. Найдите в тексте ответы на следующие вопросы:
1. When is the force acting on the wire proportional to the current and the strength of the field?
2. What instrument is a galvanometer?
III. Найдите в тексте производные от следующих слов. Укажите и части речи и переведите их на русский язык.
1. a magnet
4. to measure
5. to deflect
6. to point
8. a proportion.
IV. Перепишите и переведите на русский язык следующие предложения. Обратите внимание на глаголы “should”(в значении «должен, следует»), “would” (в сослагательном наклонении глаголом + частица «бы»):
1. From the standpoint of the electric engineer a current of a few hundred amperes would be called a medium one.
2. If a piece of wire were replaced by another one of the same length but of double cross sectional area, it would offer half its former resistance.
3. According to this rule the wire used should have as large a cross-section as possible.
4. It should be noted that this relation is true for metallic conductors.
V. Перепишите и переведите на русский язык следующие предложения.
Обратите внимание на конструкцию "Сложное подлежащее " (см. модели):
1. Though this requirement seems to be complicated, the meter is nothing more than a small electric meter.
2. The amount of the developed heat is found to be proportional to the square of the current flowing in the conductor.
3. When the resistance decreases as the temperature is raised, the substance is assumed to have a negative coefficient of resistance.
4. Overloaded wires are found to overheat.