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Tutorial for Masters.doc
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I. For statements (1-10) choose the best alternative (a, b or c) to replace the expressions in italics:

  1. The Earth’s environment is widely affected by various types of radiation ... (line 4)

A. similar B. different C. distinct

  1. The knowledge that the two fields were interdependent began with ... (line 8)

A. acquirement B. cognition C. learning

  1. He learnt that magnetism is ultimately caused by ... (line 10)

A. definitely B. finally C. eventually

  1. Later on the simultaneous though separate discoveries made by ... (line 13)

A. solitary B. ordinary C. isolated

  1. The best source of electromagnetic waves is accelerated waves. (line 18)

A. deferred B. speeded up C. decelerated

  1. They are immersed in each others electric force field.(line 21)

A. involved B. absorbed C. concerned

  1. ... the first charge after some very small finite time elapses. (line 23)

A. sovereign B. limited C. restricted

  1. These changing electric and magnetic fields generate each other ... (line 27)

A. elaborate B. produce C. oscillate

  1. ... the product of frequency and wavelength equals the speed of light. (line 32)

A. competes B. rivals C. equalizes

  1. Since life on the Earth is bathed constantly in all forms of electromagnetic radiation ... (line 34)

A. continuously B. occasionally C. rarely

II. Determine the key message of the text. Choose the best alternative (a, b, c, d or e):

A. There are different types of electromagnetic waves.

B. The theory of electromagnetic waves is constantly developing.

C. There are advantages and disadvantages of electromagnetic waves.

D. The study of electric and magnetic fields in the nineteenth century led to the understanding of electromagnetic waves.

E. A lot of scientists discovered electromagnetic waves at the same time.

Text 2 electromagnetism

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(1) Although electricity was known to the ancient Greeks, the scientific study of electricity was only really initiated in the 16th century by William Gilbert. He discovered, for example, that objects "charged" with electricity either attracted or repelled other "charged" objects. Electricity was studied with great interest. Many theories were put forward to explain it, and how it caused objects to move, and even made sparks. Scientists soon began to search for a connection between these effects and other “forces of nature”.

(2) Electricity and magnetism have been known for about 3,000 years. It was noticed long ago that when some materials are rubbed, they can attract or repel other objects. Quite separately people noticed that some natural materials seemed to have unusual powers that attracted objects with iron in them. The strange invisible forces of magnetism had puzzled people from the time magnetic rocks were discovered.

(3) During the 18th century experimenters were familiar with most of the ways electricity and magnetism behave. But the two were seen as separate. Each of them was thought to be carried by a "fluid" that passed between materials, causing the attractions and repulsions people had observed. In the first half of the 19th century an amazing discovery was made: electricity can make magnetism, and magnetism can make electricity.

(4) In 1831 Faraday discovered in one of his famous experiments that although two coils were not actually connected to each other, electricity was produced in one coil every time the electric current through the other one changed. He realized that the "induction" of electricity in the second coil could be explained only by the presence of such a magnetic effect in the iron core. Experiments of this type paved the way for an understanding of energy. Electricity and magnetism had always been two separate things, but now it was becoming clear that they could be converted one to the other.

(5) The discoveries of electromagnetism were very important to the understanding of energy. If these two "natural forces" could change from one to the other, maybe other "forces of nature" could do so too. The stage was set for the development of the Law of Conservation of Energy.

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