You are given three converignf lenses of power `P_1 = +6D, P_2 = +6D and P_3 = +12 D`. Which two lenses will you select to construct a mciroscope?

You are given the following three lenses. Which two lenses will you use as an eye piece and as an objective to construct an astronomical telescope? Give reasons.

You are given two convex lenses of short aperture having focal lengths 4 cm and 8 cm respectively.Which one of these will you use as an objective and which one as an eye piece for constructing a compound microscope?

Two lenses of power +12 D and -2D are combined together.What is their equivalent focal length?

Which of the following lenses L_1 , L_2 and L_3 will you select as objective and eyepiece for constructing best possible (i) telescope and (ii) microscope? Give reason to support your answer.

An astronomical telescope uses two lenses of power 10 D and 1 D.What is its magnifying power in normal adustment?

Two lenses of powers+15D and -5D are in contact with each other. What is the focal length of combination?

Two lenses of power 15.5 D and -5.5 D are placed in contact.What is teh focal length of the combbination?

Two thin lenses of pwer +5D and -3D are in contact. What is the focal length of the combnation?

Two lenses having powers + 6 D and - 4D are placed in contact.The power of the combintin is

Two lenses have powers + 1 D and - 2 D respectively ,The power of combination si: