1 Crore+ students have signed up on EduRev. Have you? Download the App 
A person cannot see the object distinctly, when placed at a distance less than 100cm. What is the power of the spectacles that he should use to see clearly the objects placed at 25 cm?
A far sighted person has lost his spectacles. He can read a book at usual distance by looking through a pin hole because while looking through the pin hole:
A myopic person can see things clearly if they lie between 8 cm and 100 cm from his eye. The lens will enable him to see the moon distinctly if its focal length is:
The earth takes 24 h to rotate once about its axis. How much time does the sun take to shift by 1º when viewed from the earth?
A slide projector gives a magnification of 10. If a slide of dimensions 3 cm x 2 cm is projected on the screen, the area of the image on the screen is:
What happens to the magnifying power of microscope, when its length increases?
The magnifying power of a telescope is 9. When it is adjusted for parallel rays, the distance between the objective and eyepiece is found to be 20 cm. The focal lengths of lenses are:
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?
158 videos453 docs185 tests

158 videos453 docs185 tests
