Q24 of 84 Page 322

The radius of curvature of a concave mirror is 50 cm. Where should an object be placed in the mirror, so as to form its image at infinity? Justify your answer.

Given;

Radius of Curvature(R) = 50cm;


R = 2f


⇒ 50 = 2f


⇒


Focal length = 25cm.


When an object is kept at the focus of the concave mirror then the image is formed at infinity.


This can be shown as below:


The Mirror formula is given by:



Where, F is the focal length of the mirror


v is the image distance from the pole of the mirror


u is the object distance from the pole of the mirror


On solving for v, we get



If F=u=25 cm, we get



Therefore the object should be placed at 25cm from the pole of the concave mirror to get an image at infinity.


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