If focal length of a magnifying glass in 4 cm, calculate the magnifying power for strained eye.

A compound microscope with an objective of 1.0 cm focal length and an eye-piece of 2.0 cm focal length has a tube of lengh of 20 cm.Calculate the magnifying power of the microscope,if the final image is formed at the near point of the eye.

Name a few uses of magnifying glass.

If the focal length of a converging lens is 50 cm. What is the power of the Lens ?

The focal length of the objective an astoomical telescope is 75 cm and that of the eye-piece is 5 cm.If the final image is ofrmed at the least distance of ditinct vision from the eye,calculate the magnifying power of the telescope.

Why do we prefer a magnifying glass of smaller focal length?

A small telescope has an objective lens of focal length 144cm and an eyepiece of focal length 6.0cm. What is the magnifying power of the telescope? What is the separation between the objective and the eyepiece?

A small telescope has an objective lens of focal length 140cm and an eyepiece of focal length 5.0cm. What is the magnifying power of the telescope for viewing distant objects when- the final image is formed at the least distance of distinct vision (25cm)?

A small telescope has an objective lens of focal length 140cm and an eyepiece of focal length 5.0cm. What is the magnifying power of the telescope for viewing distant objects when- the telescope is in normal adjustment (i.e., when the final image is at infinity)?

Is focal length of eye lens fixed? If not, why?