The distance of distinct vision of a person is 50 cm. He wants to read a book placed at 25 cm. What should be the focal length of the spectacles?
Calculate the volume of a book which is 25 cm in length, 12 cm in breadth and 2 cm in height in metre cube
The thickness of a science book is 3cm. If 10 such books are piled one over another, the total height of the books is: