Math, asked by HRShritik, 1 year ago

what power of a lens will change the reading distance from 1m to 0.25 m?

Answers

Answered by Tushakar

1 dioptre to 4 dioptre

HRShritik: Ans is 5D

Tushakar: how this possible

Tushakar: because power of lens is inversely proportional to the focal length (in m)

Tushakar: and you can easily check by this formula

HRShritik: first try to understand the question

Tushakar: please give the solution if you know briefly

Answered by Ysudeeksha

Answer:

Using mirror formula:

Formula.

1/f = 1/v + 1/u. where f is the focal length, u is object distance.

v is distance of image.

The expression which shows the relation between u, v and f is called mirror formula for v= -0.25 u = -1cm.

you will get focal length f= -1/5

power P = -(1/f)

so p= +5D

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