Контрольная работа на тему ИДЗ. Профессиональный иностранный язык.

Фрагмент текста работы:

READING
Text 1
1. Read the text, and match the questions (A–F) to the numbered spaces (1–5), as in the example (0).
A. How is current often described in engineering or household applications?
B. What current reverses direction repeatedly?
C. What concept was introduced by Michael Faraday?
D. What is alternating current affected by?
E. What is direct current?
F. What is the time-averaged value of an alternating current?

0. In engineering or household applications, current is often described as being either direct current (DC) or alternating current (AC). These terms refer to how the current varies in time.
E. 1. Direct current, as produced by example from a battery and required by most electronic devices, is a unidirectional flow from the positive part of a circuit to the negative. If, as is most common, this flow is carried by electrons, they will be travelling in the opposite direction.
B. 2. Alternating current is any current that reverses direction repeatedly; almost always this takes the form of a sinusoidal wave. Alternating current thus pulses back and forth within a conductor without the charge moving any net distance over time.
F. 3. The time-averaged value of an alternating current is zero, but it delivers energy in first one direction, and then the reverse.
D. 4. Alternating current is affected by electrical properties that are not observed under steady state direct current, such as inductance and capacitance. These properties, however, can become important when circuitry is subjected to transients, such as when first energised.
C. 5. The concept of the electric field was introduced by Michael Faraday. An electric field is created by a charged body in the space that surrounds it, and results in a force exerted on any other charges placed within the field.