CBSE Guess > Papers > Important Questions > Class X > 2008 > Science > Science By :- Chetan Singh Kushwah

Mathematics (Arithmetic Progression)

Q. 1. The magnification produced by a concave lens is always positive / negative.

Q. 2. The focal length of a lens of power + 1.25 D is _____ and it’s a converging / diverging lens.

Q. 3. A concave lens of focal length 15 cm forms an image 10 cm from the lens? How far is the object placed from the lens?

Q. 4. The stars seem to be slightly higher that they actually are. Why?

Q. 5. Define power of a lens. Why the power of a convex is positive while that of a concave lens is negative?

Q. 6. Define
(a) Power of accommodation (b) Least Distance of Distinct Vision

Q. 7. Write any four uses of concave mirrors.

Q. 8. Why does the sky appear dark instead of blue to an astronaut?

Q. 9. What is hypermetropia? How can it be corrected? How is it different from presbyopia?

Q. 10. An object of size 3 cm is placed at a distance of 15 cm from a convex lens of focal length 10 cm. Calculate the distance and the size of the image so formed. What will be the nature of image formed?

Q. 11. A converging mirror forms a real image of height 6 cm of an object of height 2 cm placed 20 cm away from the mirror. Find the image distance and the focal length of the mirror.