C.
Activities
Look through the text and resume it in writing (no more than 250-300
words in total).
76
Text 4. Electromagnetic induction and Faraday`s laws
«It is right that we should stand by and act on our
principles; but not right to hold them in obstinate
blindness, or retain them when proved to be erroneous»
Michael Faraday
PRE-READING
Before we study the motion of an electromagnetic field in detail, let’s have
some fun with electricity. In a small group discuss these problems and make
notes of your main points. Then compare your notes.
1)
How can you distinguish a magnet from a non-magnetized metal bar
of the same size and material using no external means?
2. In 1722, George Graham discovered, by watching a compass
needle, that the magnetic field of the Earth shows daily variations.
Can you imagine why these variations occur?
2)
If even knocking on a wooden door is an electric effect, we should be
able to detect fields when doing so. Can you devise an experiment to
check this?
3)
Birds come to no harm when they sit on unprotected electricity lines.
Nevertheless, one almost never observes any birds on tall, high
voltage lines of 100 kV or more which transport power across longer
distances. Why?
5. A PC or a telephone can communicate without wires, by using
radio waves. Why are not these and other electrical appliances able to
obtain their power via radio waves, thus eliminating power cables?
Do you know the reasons?
Active vocabulary
Word
Pronunciation
Translation
circuit, n.
/ˈsɜːkɪt/
цепь, контур
copper wire
/ˈkɒpər waɪər/
медная проволока, провод
deflect, v.
/dɪˈflekt/
изменять направление,
отклоняться от курса
electrolysis, n.
/ɪˌlekˈtrɒləsɪs/
электролиз
electromotive
/ɪˌlektrəˈməʊtɪv fɔːs/
электродвижущая сила
force/emf
77
equation, n.
/ɪˈkweɪʒən/
уравнение
flux linkage
/flʌksˈlɪŋkɪdʒ/
потокосцепление
hence, adv.
/hens/
следовательно, syn. therefore,
thus
induce, v.
/ɪnˈdjuːs/
индуцировать, наводить
induced current
/ɪnˈdjuːst ˈkʌrənt/
индуцированный ток
induction cooker
/ɪnˈdʌkʃən ˈkʊkər/
индукционная плита
needle, n.
/ˈniːdl/
стрелка, syn. Index
rotate, v.
/rəʊˈteɪt/
вращать(ся)
voltage, n.
/ˈvəʊltɪdʒ/
электрическое напряжение
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