- •Part I
- •Text. Physics and physical phenomena
- •Laboratory Exercises
- •Additional Material
- •M. V.Lomonosov
- •Exercises
- •Laboratory Exercises
- •Additional Material
- •Measurement of Volume
- •Text. The metric system
- •Dimensions of a Solid Body
- •Laboratory Exercises
- •Additional Material
- •Origin of the Metric System
- •Text. The kinetic theory and the three states of matter
- •3 Not to matter — не иметь значения will make full use — займут
- •Exercises
- •Laboratory Exercises
- •Additional Material
- •Text. Mass and weight
- •3. Much, more, the most; little, less, the least; good, bet ter,
- •4, .,. Er than, more ... Than
- •5. At, on, over .., etc.
- •Exercises
- •Laboratory Exercises
- •Additional Material
- •Text, force, work, energy and power
- •Exercises
- •Additional Material
- •1. Have supported, has altered....
- •2. Energy can be converted...
- •Exercises
- •Laboratory Exercises
- •Additional Material
- •Isaac Newton
- •Text. Heat
- •1. Heat is known to be a form of energy.
- •2. You place, you placed, you have placed. They take, they took, they have taken.
- •3. Newton began to think about heat.
- •Exercises
- •Laboratory Exercises
- •Additional Material
- •Text. Transmission of heat
- •Exercises
- •Laboratory Exercises
- •Additional Material
- •Good and Bad Conductors of Heat
- •Text. Calorimeters
- •1. It is usual to transfer ...
- •2. There is; is there; there is no ...
- •3. The setting up of ...; the reading of ...
- •Exercises
- •Laboratory Exercises
- •Additional Material
- •Text. Wave motion and sound
- •1. It does not move forward but returns again...
- •2. It is evident, it is clear.
- •Exercises
- •Additional Material
- •Text. Light
- •1. It becomes red-hot, it is the reason, it was cold...
- •2. High temperature produced by..., in a substance called... . Exercises
- •Laboratory Exercises
- •Additional Material
- •Text. Reflection and refraction of light
- •1. Do bodies emit? Does he make? Did it represent?
- •2. Have they shown? Had he travelled? Was it reflected? Is he going? Exercises
- •Laboratory Exercises
- •Additional Material
- •Text. Lenses
- •1. After leaving the lens...
- •Exercises
- •Additional Material
- •Text. Simple cell
- •1. The twitching of; the reading of...
- •Exercises
- •Laboratory Exercises
- •Additional Material
- •Voltaic Cells
- •Text. The accumulator
- •1. A plate containing, a plate being immersed...
- •2. Achieved by connecting; determined by testing...
- •Exercises
- •Additional Material
- •Text. Principle of electric motor
- •1. They are used to pull...
- •2. When viewed, while doing...
- •Exercises
- •Laboratory Exercises
- •Additional Material
- •Electric Bell Circuit
- •Text. Moving-coil ammeter and voltmeter
- •Exercises
- •Laboratory Exercises
- •Additional Material
- •Moving-Coil Galvanometer
- •Text. Electromotive force
1. After leaving the lens...
On entering the lens the rays are bent toward the normal. On leaving the lens the rays are bent away from the normal. They appear on leaving the lens to come from a point behind the lens.
Exercises
1. Listen, read and translate the text.
2. Answer the following questions in a written form:
1. How may lenses be classified? 2. When do the rays converge to the principal focus? 3. When does the lens converge the rays rapidly? 4. What gives the lens a short focal length? 5. When has the lens a long focal length? 6. When are the emerging rays bent away from the principal axis?
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3. Make up and write all possible questions to the following sentences:
1. The unit used to denote (measure) quantity or amount of light is the lumen. 2. A lumen is the amount of light falling on a surface that has an area of 1 sq ft when every point of the surface is 1 ft from a point source of light of 1 candle. 3. The light may be absorbed by the material. 4. The material which sends no light on towards the eye and so looks black is said to be perfectly opaque. 5. Some light may pass through the substance. 6. The light undergoes rectilinear propagation.
4. Copy the following sentences putting "axis", "beam", "virtual", "focus", "lens", "principal", "rays", "converge", "diverging", "real" in the blanks:
1. A simple ... is usually a piece of glass bounded by spherical surfaces. 2. The principal ... of a lens is the line joining the centres of curvature of its surfaces. 3. If a parallel ... of light, parallel to the ... axis, is incident on a converging lens, the rays, after passing through the lens, all ... to a point on the axis which is called the principal ... . 4. In the case of a diverging lens, the ... will spread out after passing through the lens, as if ... from a focus behind the lens. 5. The principal focus is thus ... for a converging lens and ... for a diverging lens.
5. Find English equivalents to the following word combinations:
естественный источник света, точечный источник света, однородная среда, распространение света, скорость света, световой луч, световые пучки, расходящийся пучок, сходящийся пучок, параллельный пучок, мнимый фокус, действительный фокус, угол падения, отражение света, угол отражения, поверхность плоского зеркала, вогнутая линза, выпуклая линза, преломление света, оптическая ось, фокус линзы, фокусное расстояние линзы, собирающая линза, рассеивающая линза, падающий фронт волны.
6. Answer the questions in a written form choosing the necessary gerundial construction given in the table:
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goes is known as a real focus. 3. The lens which converges the rays after leaving it is called a converging lens.
13. Listen to this short dialogue and learn it by heart:
— Lenses are magnifying glasses which are made of transparent material, aren't they?
— Certainly they are. This gives the lenses widely using in optical instruments. What kind of lenses do you know?
— There are many of them. Although they differ much in form they may be divided into two classes.
— I see. According to the way in which they act on a parallel beam of light they are divided into converging and diverging lenses.
— Yes, they are. By the way, they have some focuses too.
— Of course. A point to which the rays converge is called a principal focus. And what else?
— An apparent focus is a point from which the light does not really come. What is a virtual focus?
- It is a point from which the light appears to come. Is there a real focus?
— Certainly, it is. A point through which the light actually goes.
14. Suggested topics for oral narration:
1. Distinguish between a converging lens and a diverging lens. Describe, with the help of diagrams, their difference.
2. What is an apparent and real focuses? Show, by means of a ray diagram, that any lens has two focuses.