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# 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.

Answer :

1.43 m, 2.0 m

Height of the image, h_{1}= 20cm

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

Height of the image, h_{2} = 50cm

As we know,

Using mirror formula,

Hence the focal length is 144cm.

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