Question

A compound microscope consists of an objective lens with focal length $1.0 \,cm$ and eye piece of focal length $2.0\, cm$ and a tube length $20 \,cm$ the magnification will be

• A. $100$
• B. $200$
• C. $250$
• D. $300$

Answer 1

Answer: (C)

$250$

Answer 2

Magnification, of compound microscope $m = m_0 \times m_e = (\frac{L}{f_0})\times(\frac{D}{f_e})$ Here, $L = 20\, cm, D = 25 \,cm$ (near point), $f_0 = 1 \,cm$ and $f_e = 2 \,cm$ $\therefore m = \frac{20}{1}\times \frac{25}{2} = 250$