Increase your vocabulary

Exercise 1. Arrange the following words in pairs of antonyms.

Negative, light, top, shade, positive, small, diverge, base, more, thin, less, converge, thick, large.

Exercise 2. Translate the following words and word combinations into Russian.

a) recognize, diffuse, finite, converge, join, diverge, curvature, enlargement, truncated, incident;

b) image quality, image formation, light intensity, light diffraction, light propagation, pinhole size, image enlargement, surface curvature, object point, lens axis, light beam;

c) luminous point, straight line, truncated prism, bright image, practical value, coarse pinhole, certain limit, diffuse image, finite size, further enlargement, ground glass, dotted lines, infinite number, opaque screen, fine pinhole.

Exercise 3. Remember the meaning of the terms that you have found in the text.

Focus is a meeting point of rays of light; point, distance at which the sharpest outline is given (to the eye, through a telescope, through a lens, etc.).

Lens is a piece of glass or glass-like substance with one or both sides curved for use in spectacles, cameras, telescopes and other optical instruments.

Prism is a solid figure with similar equal and parallel ends and which are parallelograms body of this form made of glass which breaks up white light into the colours of the rainbow.

Diffraction is scattering of waves in back of a solid object after they strike it.