CBSE Class 10 Science 2016 Term II Outside Delhi Set 3

Question : 10 of 11

Marks: +1, -0

The image formed by a spherical mirror is real, inverted and is of magnification - 2 . If the image is at a distance of

30 {\cm}

from the mirror, where is the object placed ? Find the focal length of the mirror. List two characteristics of the image formed if the object is moved

10 {\cm}

towards the mirror.

Solution:

Given,

m=-2, v=-30 {\cm}

We know that,

m\;=\;{-v}/{u}

-2\;=\;{30}/{u}

u\;=-15 {\cm}

Now,

f=\;{u v}/{u+v}=\;{-15 ×-30}/{-15-30}=\;{450}/{-45}=-10 {\cm}

If the object is shifted

10 {\cm}

towards the mirror then,

u=-5 {\cm}

, i.e., object is between pole and focus, thus image formed will be virtual, erect and magnified.

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