IV. Match (21-30) with their definitions (A-L). There are two definitions that you do not need to use.

I. Read the text. Choose the most suitable heading from the list (A-G) for each part (1-5) of the text. There are two extra headings which you do not need to use.

A.The Interdependence of the Two Fields.

B.Physical Characteristics of Electromagnetic Waves.

C.Different Types of Radiation.

D.Electromagnetic Waves Propagation.

E.Ampere’s Law.

F.The Definition of Electromagnetism.

G.The Development of Quersted’s Theory.

II. Read the text. For statements (6-15) choose “True” if the statement is true according to the text, “False” if the statement is false:

6.Electromagnetism is the physics of the electromagnetic field exerting a force oncharged particles.

7.The concept of electricity was considered at the beginning of the nineteenth century.

8.Hans Christian Quersted was the first to discover electromagnetism.

9.Michael Faraday and Joseph Henry made the discovery of electromagnetic induction.

10.Maxwell explained electromagnetic waves by joining electricity, magnetism and optics into one theory.

11.The origin of the electromagnetic waves is microwaves.

12.When one charge starts to vibrate, the second one undergoes the influence of the magnetic field.

13.In vacuum electromagnetic waves have the velocity of light.

14.There is the interrelation between frequency, wavelength and velocity of electromagnetic waves.

15.Vibration wave is connected with frequency.

III. Read the text. For questions (16-20) choose the correct answer (A, B, C or D).

16)Electromagnetism is …

a)the power of electrically charged particles interaction.

b)the acceleration of charges in a discharge tube.

c)the propagation of waves in space.

d)the theory of light.

17)Hans Christian Quersted was the first who discovered …

a)electromagnetic waves.

b)the cause of magnetism.

c)alternating electric current.

d)the speed of light.

18)James Maxwell’s theory was …

a)the beginning of electromagnetism

b)the branch of optics.

c)the development of gamma rays theory.

d)the result of previous discoveries.

19)An accelerated charge can change …

a)its speed and direction.

b)such medium as glass.

c)radio waves.

d)a direct charge.

20)The fastest speed of electromagnetic waves is …

a)in air.

b)in salt water.

c)in vacuum.

d)in water.

IV. Match (21-30) with their definitions (A-L). There are two definitions that you do not need to use.

21.	to define	A.	the emission or transfer of radiant energy
22.	to accelerate	B.	to produce electricity
23.	radiation	C.	to move or swing from side to side regularly
24.	to propagate	D.	the total amount of electricity
25.	interdependent	E.	to describe the nature, or essential qualities of smth.
26.	simultaneous	F.	an intervening substance
27.	to oscillate	G.	relating to two or more things dependent on each other
28.	to generate	H.	to correspond to
29.	medium	I.	to make or become greater in size
30.	to equal	J.	to move through in the form of a wave
		K.	to increase the velocity of smth.
		L.	occurring, existing, or operating at the same time

Supplementary Tasks :

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.similarB.differentC.distinct

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

A.acquirementB.cognitionC.learning

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

A. definitely B.finallyC.eventually

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

A.solitary B.ordinary C.isolated

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

A.deferredB.speeded upC.decelerated

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

A.involvedB.absorbedC.concerned

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

A.sovereignB.limitedC.restricted

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

A.elaborateB.produceC.oscillate

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

A.competesB.rivalsC.equalizes

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

A.continuouslyB. occasionallyC.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

(1)Although electricity was known to the ancient Greeks, the scientific study of electricity was only really initiated in the 16^th 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 18^th 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 19^th 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.