Question

The magnifying power of a simple microscope A is 1.25 less than that of a simple microscope B. if the power of the lenses used in B is 25 D, find the power of lens used in A. Given that distance of distinct vision is 25cm

Answer 1

Answer:

given = magnifying power(A)= 1.25

            magnifying power(B) =25D

            distance = 25cm

to find =  find the power of lens used in A.

solution =

$MA = 1+D/fA \\MB = 1 + D/fb \\\\MB - MA = \frac{D}{fB} -\frac{D}{fA} \\=1.25\\ \frac{D}{fB} -\frac{D}{fA} \\=1.25\\ = \\1.25/D = 1.25/0.25 = 5D \\PA = PB -5D = 25D -5D = 20D$

so, the power of lense used in A is 20D