6. The spherical mirror formula is written as :
(a) (1/v) – (1/u) = 1/f
(b) 1/f = 1/(f + v)
(c) (1/v) + (1/u) = 1/f
(d) f = R/2
7. The final image formed by an terrestrial telescope is :
(a) Erect
(b) Inverted
(c) Sometimes erect, sometimes inverted
(d) None of these
8. The magnifying power of an telescope can be increased by using :
(a) Eye lens of large focal length
(b) Objective of large focal length
(c) Objective of short focal length
(d) None of these
9. The unit of Power of a lens is :
(a) centimetre
(b) metre
(c) dioptre
(d) lux
10. A Lens of Power of -2.5 D, Then its focal length will be :
(a) 0.4 m
(b) -0.4 m
(c) 0.2 m
(d) -0.2 m
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Ray Optics » Exercise - 115. An object is placed at a distance of 40 cm infront of concave mirror of focal length 20 cm. The image produced ______ . (a) Virtaul and inverted. (b) Real and erect. (c) Real, inverted and diminished. (d) Real, inverted and same size of an object.- Ray Optics » Exercise - 1 1. Image formed by a convex mirror is : (a) Real (b) Inverted (c) Virtual, erect and diminished (d) None of these
- Ray Optics » Exercise - 12. Image formed by a concave mirror is : (a) Real (b) Inverted (c) Real, Inverted and equal in size of lmage (d) None of these
- Ray Optics » Exercise - 14. The focal length (t) of a spherical mirror if radius of curvature R is : (a) R/2 (b) R (c) 3/2 R (d) 2 R
- Ray Optics » Exercise - 15. A concave mirror has radius of curvature of 0.2 m its focal length is : (a) -0.2 m (b) -0.1 m (c) 0.1 m (d) 0.2 m