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# An Object of 5.0 Cm Size is Placed at a Distance of 20.0 Cm from a Converging Mirror of Focal Length 15.0 Cm. at What Distance from the Mirror Should a Screen Be Placed to Get the Sharp Image? Also Calculate the Size of the Image. - CBSE Class 10 - Science

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ConceptReflection of Light Image Formation by Spherical Mirrors - Concave Mirror

#### Question

An object of 5.0 cm size is placed at a distance of 20.0 cm from a converging mirror of focal length 15.0 cm. At what distance from the mirror should a screen be placed to get the sharp image? Also calculate the size of the image.

#### Solution

Concave mirror is a converging mirror.
Distance of the object from the mirror 'u' = -20 cm
Height of the object 'ho' = 5 cm
Focal length of the mirror 'f' = -15 cm
We have to find the distance of the image 'v' and the height of the image 'hi'.
Using the mirror formula, we get
1/f=1/v+1/u
1/-15=1/v+1/-20=1/v-1/20
or 1/v=1/20-1/15
or 1/v=(3-4)/60=1/60
or v=-60 cm
Thus, the image is at a distance of 60 cm in front of the mirror.
Now, using the magnification formula, we
get
m=-v/u=h_i/h_o
or h_i/5=-(-60)/-20
or h_i/5=-3
or h_i =-3xx5=-15 cm
Therefore, the height of the image will be 15 cm, and the negative sign shows that the image will be formed below the principal axis
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Solution An Object of 5.0 Cm Size is Placed at a Distance of 20.0 Cm from a Converging Mirror of Focal Length 15.0 Cm. at What Distance from the Mirror Should a Screen Be Placed to Get the Sharp Image? Also Calculate the Size of the Image. Concept: Reflection of Light - Image Formation by Spherical Mirrors - Concave Mirror.
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