Question

A person needs a lens of power -3.5 D for distant viewing. His doctor prescribes a correction of +0.5 D in the near vision section of his bi-focals.
(i) What's the focal length of the distant viewing part of his lens?
(ii) What's the focal length of the near vision section of the lens?

Answer 1

If we need magnification of 375 from a microscope of tube length 15 cm and objective of focal length 0.5 cm, what focal length of eye-piece should we use?

Solution:

Magnification m = 375

Length of the tube L = 15 cm

Focal length of the objective fo = 0.5 cm

We know that

Extra-Questions-for-class-10-Science- Human-Eye-and-Colourful-World-Q18

Answer 2

Hi,

Use f=1/p

f=1/-3.5

f=1/0.5

You vll get the answer

Hope this helps you

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