Question

With the help of a ray diagram, show how a compound microscope forms a magnified image of a tiny object, at least distance of distinct vision. Hence derive an expression for the magnification produced by it.

Answer 1

Image formation by compound microscope at the least distance of distinct vision:

Expression for magnification:

For objective,

Magnification = m_o = `"P'Q'"/"PQ" = (-"v")/"u"`

When the image is formed at the least distance of distinct vision, then

Magnification = m_e = `(1 + "D")/"f"_"e"`

So, final magnification = m = m_o × m_e = `"v"/"u" (1 + "D"/"f"_"e")`