Q1. The magnifying power of a telescope is 9.0. when it is focused for parallel rays, then the distance between its objective and eye-piece is 20cm. The focal lengths of lenses will be .............
Q2. A plane convex lens of f = 20cm is silvered at plane surface. New f will be .........
(A) 20
(B) 40
(C) 30
(D) 60
Q3. A ray of light from denser medium strikes a rare medium at angle of incidence i. The reflected and refracted rays make an angle 90deg with each other. The angle of reflection and refraction are r and r' respectively. The crictical angle is ...............
Q5. The radius of curvature of convex surface of a thin plane-convex lens is 15 cm and refractive index of its material is 1.6. The power of the lens will be ........
(A) 6 D
(B) 5 D
(C) 4 D
(D) 3 D
Q6. A ray of light passes through a prism having refractive index (n = √2),Suffers minimum deviation. If angle of incident is double double the angle of refraction within prism then angle of prism is ..........
(A) 30deg
(B) 60deg
(C) 90deg
(D) 180deg
Q7. An air bubble inside glass slab (n=1.5) appear from one side at 6 cm and from other side at 4 cm. Then the thickness of glass slab is ........... cm
(A) 5
(B) 10
(C) 15
(D) 20
Q8.The magnifying power of objective of a compound microscope is 5.0. If the magnifying power of microscope is 30, then the magnifying power of eye-piece will be .....
(A) 3
(B) 6
(C) 9
(D) 12
Q9. Light of certain colour contain 2000 waves in the length of 1 mm in air. What will be the wavelength of this light in medium of refractive index 1.25 ?
(A) 1000 A
(B) 2000 A
(C) 3000 A
(D) 4000 A
Q10.When the length of microscope tube increaases, its magnifying power.........
(A) decrease
(B) increase
(C) does not change
(D) none of these
ANSWER
(Ans 1.) B
(Ans 2.) C
(Ans 3.) D
(Ans 4.) C
(Ans 5.) C
(Ans 6.) C
(Ans 7.) C
(Ans 8.) B
(Ans 9.) D
(Ans 10.) A