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1. Which of the following is an example of defects of aberrations in objectives?
- a) Curvature of the field, astigmatism
- b) Chromatic and spherical aberrations
- c) Distortion, lateral color, coma
- d) All of the above
2. Which of the following is incorrect for spherical aberrations?
- a) Spherical aberrations arise due to greater power in the inner portion of spherical surface than outer portion
- b) It can be corrected by combinations of convergent and divergent lens elements
- c) It causes some of the light to diffuse out into the ring structure from the central spot
- d) It causes loss of contrast in normal microscope preparation
3. In which kind of aberrations cushion shape and barrel shape alterations are found to appear?
- a) Curvature of field
- b) Astigmatism
- c) Distortion
- d) Spherical aberration
4. What is the correct reason for curvature of the field?
- a) Greater power in the outer portion of the spherical surface than in the inner portion
- b) Lens surface having different magnifications at the marginal and the central portion of the
image - c) Marginal portion of the image come to focus at a different distance from those of central
portion of the image - d) All of the above
5. _______ in the center of the field is an indication of damage to the objective:
- a) Lateral color
- b) Coma
- c) Stigma
- d) All of the above
6. Due to dispersive power of the lens, shortest waves refracted _ and longest waves
refracted __:
- a) Less, most
- b) Most, less
- c) Less, less
- d) Most, most
7. color rays cross the lens axis first and _ color rays cross the lens axis last:
- a) Blue-violet, red
- b) Red, yellow-green
- c) Green, yellow
- d) Red, indigo
8. Formation of halos is a characteristic of __ aberration:
- a) Spherical
- b) Lateral color
- c) Distortion
- d) Chromatic
9. How chromatic aberration can be eliminated?
- a) Reducing the aperture of lens
- b) Using a lens composed of more than one material
- c) Both of the above
- d) Use of prism lens
10. If two optical glasses are selected to image light of two different wavelength at the same focal point, the lens is said to be _____
- a) Apochromatic
- b) Achromatic
- c) Semi-apochromatic
- d) Fluorite
11. ________ objective is a lens system that is corrected for light of three different wavelengths:
- a) Apochromatic
- b) Achromatic
- c) Semi-apochromatic
- d) All of the above
12. Semi-apochromatic and apochromatic objectives are composed of________ mineral in
combination with lenses of optical glasses:
- a) Fluoride
- b) Fluorite
- c) Any halide
- d) None of the above
13. Faint blue or yellow color is exhibited through _______ objective:
- a) Apochromatic
- b) Achromatic
- c) Semi-apochromatic
- d) All of the above
14. Due to shifting of focus faint green and pink color halos are observed. Which kind of objective does produce it?
- a) Apochromatic
- b) Achromatic
- c) Semi-apochromatic
- a) Fluorite