Physics Section
26. The refractive indices of glass and water with respect to air are 3/2 and 4/3 respectively. If speed of light is 2×10^8 m/s. Find the speed of light in water.
(A) 2.25×108 m/s
(B) 2.00×108 m/s
(C) 1.00×108 m/s
(D) 2.50×108 m/s
27. A divergent lens has a focal length of 20cm. At what distance should an object of height 4cm from the optical center of the lens be placed so that it’s image is formed 10cm away from the lens.
(A) U = -10cm
(C) U = +10cm
(B) U = -20cm
(D) U = -15cm
28. A student wants to obtain an erect image of an object using a concave mirror of 10cm focal length. What will be the distance of the object from the mirror?
(A) Less than 10cm
(B) Equal to 10cm
(C) between 10cm and 20cm
(D) More than 20 cm
29. Two concave lenses P and Q have focal length 0.50 cm and 0.40 cm respectively. Which of the following is true about the combined power of the two lenses?
(A) P is equal to 4.5D
(B) P is less to 4.5D
(C) P is more than 4.5D
(D) P can not be determined from the information given
30. A person with myopia eye can’t see object beyond 1.2m distinctly. What should be the type of corrective lens used to restore proper vision?
(A) F = 1.2m
(B) F = 1.5m
(C) F = 1.0m
(D) F = 12m