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  • The distance  between the focus of a concave mirror and an object is doubled and along with that the distance between the focus of the same mirror and the image formed is also doubled ; so the

The distance  between the focus of a concave mirror and an object is doubled and along with that the distance between the focus of the same mirror and the image formed is also doubled ; so the focal length will be

Option: 1

2 times than the previous


Option: 2

Same


Option: 3

4 times than the previous


Option: 4

8 times than the previous


Answers (1)

best_answer

Let us assume that the distance in between the focus of the concave mirror and the object is “x”And the distance in between the focus of the mirror and the image formed is “y”And the focal length is “f” 

From Newton’s formula of mirror we can define
xy= f^{2}

Now “x” has became “2x” and “y” has became “2y”

So the  updated focal length will be

f^{2}= 2x.2y
\Rightarrow f^{2}=4xy
\Rightarrow f=2\sqrt{xy}
From here you can see that the focal length becomes double

 

Posted by

Ritika Harsh

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