Physics, asked by Alizina, 1 year ago

A 50cm tall object is at a very large distance from a diverging lens . A virtual,erect and diminished image of the object is formed at a distance of 20cm in front of the lens . how much is the focal length of the lens

Answers

Answered by Anonymous

It's obvious from the relation, $\frac{1}{v}-\frac{1}{u}=\frac{1}{f}$ , focal length is 20cm. Actually, -20cm to be more appropriate, according to the sign convention and all.

Alizina: BUT how? can u explain it more elaborately?

shubham689: i will explain u

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Alizina: someone explain it fast please

Anonymous: Actually, the focal length of lens is defined as "When an object is placed at infinity, the point where the image is formed is called its focus."

Anonymous: Distance from optical centre to focus is called focal length.

Alizina: i know that but how these things are related to this numerical

Alizina: by applyong which formula u have got this answer?

Anonymous: I've edited it. You can see the formula, right?

Alizina: but we are given only v = -20cm in this question

Answered by bappilahri

It's obvious from the relation,, focal length is 20cm. Actually, -20cm to be more appropriate, according to the sign convention and over all.

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