A camera lens of focal length 5 cm is mounted on a fine screw thread for adjusting the focus.What range of movement is neede,if the amer ais to be able to take sharp photographs at 1 m as well as from great distances?

A card sheet divided into squares each of size 1 mm^2 is being viewed at a distance of 9 cm through a magnifying glass (a converging lens of focal length 10 cm) held close to the eye. What should be the distance between the object in converging lens and the magnifying glass if the virtual image of each square in the figure is to have an area of 6.25 mm^2 . Would you be able to see the squares distinctly with your eyes very close to the magnifier ?

A man with normal near point (25 cm) reads a book with small print using a magnifying glass: a thin convex lens of focal length 5 cm- What is the closest and the farthest distance at which he should keep the lens from the page so that he can read the book when viewing through the magnifying glass?

A person with a normal near point (25 cm) using a compound microscope with objective of focal length 8.0 mm and an eyepiece of focal length 2.5cm can bring an object placed at 9.0mm from the objective in sharp focus. What is the separation between the two lenses? Calculate the magnifying power of the microscope.

In figure S is a monochromatic point source emitting light of wavelength lambda=500 nm. A thin lens of circular shape and focal length 0.10 m is cut into two identical halves L_(1) and L_(2) by a plane passing through a doameter. The two halves are placed symmetrically about the central axis SO with a gap of 0.5 mm. The distance along the axis from A to L_(1) and L_(2) is 0.15 m , while that from L_(1) and L_(2) to O is 1.30 m. The screen at O is normal to SO. (a) If the 3^(rd) intensity maximum occurs at point P on screen, find distance OP.

In figure S is a monochromatic point source emitting light of wavelength lambda=500 nm. A thin lens of circular shape and focal length 0.10 m is cut into two identical halves L_(1) and L_(2) by a plane passing through a doameter. The two halves are placed symmetrically about the central axis SO with a gap of 0.5 mm. The distance along the axis from A to L_(1) and L_(2) is 0.15 m , while that from L_(1) and L_(2) to O is 1.30 m. The screen at O is normal to SO. (b) If the gap between L_(1) and L_(2) is reduced from its original value of 0.5 mm, will the distance OP increases, devreases or remain the same?

A boy is trying to start a fire by focussing sunlight on a piece of paper using an equiconvex lens of focal length 10 cm.The diamerter of the sun is 1.39 xx 10^9 m and its mean distance form the earth is 1.5 xx 10^(11) .What is the diameter of the sun's image on the paper?

A myopic adult has a far point at 0.1m. His power of accomodation is 4 dioptres What is his near point without glasses? (Take the image distance from the lens of the eye to the retina to be 2 cm).

A myopic adult has a far point at 0.1m. His power of accomodation is 4 dioptres What is his near point with glasses? (Take the image distance from the lens of the eye to the retina to be 2 cm).

An object is placed at a distance of 1.5 m from a screen and a convex lens is interosed between them .the magnification produced is 4.What is the focal length of the lens?

A myopic adult has a far point at 0.1m. His power of accomodation is 4 dioptres What power lenses are required to see distant objects? (Take the image distance from the lens of the eye to the retina to be 2 cm).