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A thin lens is placed 50cm from an illustrated ... - WAEC Physics 2009 Question

A thin lens is placed 50cm from an illustrated object. The image produced has linear magnification of \(\frac{1}{4}\). Calculate the power of the lens in dioptres
A
2.5D
B
5.0D
C
10.0D
D
25.0D
correct option: c

(\frac{1}{v} = \frac{1}{u})

m = (\frac{v}{u} = \frac{1}{4} = \frac{v}{50})

v = 12.5

But (\frac{1}{v} + \frac{i}{u} = \frac{1}{f})

= (\frac{1}{50} + \frac{1}{12.5} = f)

f = 10m

P = (\frac{100}{10} = 10D)

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