Entry Test MCQ :: Optical Instruments

11.  Magnifying power of simple microscope
A. increase with increase in focal length B. increase with decrease in focal length
C. no effect with decrease or increase with focal length D. list distance of distinct vision

12.  Image of an object 5 mm high is only 1 cm high. Magnification produced by lens is
A. 0.5 B. 0.2
C. 1 D. 2

13.  The least distance of distinct vision for a normal eye is
A. 15 cm B. 25 cm
C. 30 cm D. 40 cm

14.  Least distance of distinct vision
A. increases with increase in age B. decreases with increase in age
C. neither increases nor decreases D. becomes infinite after 60 years

15.  If a convex lens of large aperture fails to converge the light rays incident on it to a single point, it is said to suffer from
A. chromatic aberration B. spherical aberration
C. both spherical and chromatic D. distortion

16.  Two convex lenses of equal focal length f are placed in contact the resultant focal length of the combination is
A. zero B. focus
C. 2 f D. f/2

17.  A convex lens of focal length f1 and a concave lens of focal length f2 are placed in contact. The focal length of the combination is
A. f2 + f1 B. f2 - f1
C. f1f2/f2+f1 D. f1f2/f1-f2

18.  Final image produced by a compound microscope is
A. real and inverted B. real and erect
C. virtual and erect D. virtual and inverted

19.  For normal adjustment, length of astronomical telescope is
A. fo + fe B. fo - fe
C. fo / fe D. fe / fo

20.  In multimode step index fibre the refractive index of core and cladding is
A. same B. different
C. zero D. different with refractive index of core higher than cladding

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