Q2 of 123 Page 412

A concave mirror forms an image of 20 cm high object on a screen placed 5.0

m away from the mirror. The height of the image is 50 cm. Find the focal length of the mirror and the distance between the mirror and the object.


1.43 m, 2.0 m

Height of the image, h1= 20cm


The distance of screen from the mirror, v = 5.0 m


Height of the image, h2 = 50cm



As we know,





Using mirror formula,





Hence the focal length is 144cm.


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