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# At What Distance from a Concave Mirror of Focal Length 10 Cm Should an Object Be Placed So That: Its Real Image is Formed 20 Cm from the Mirror? - CBSE Class 10 - Science

ConceptReflection of Light Image Formation by Spherical Mirrors - Concave Mirror

#### Question

At what distance from a concave mirror of focal length 10 cm should an object be placed so that:

its real image is formed 20 cm from the mirror?

#### Solution

Given

It is a concave mirror.

f=-10 cm

v=-20 cm

Since the image is real and forms in front of the mirror, the equation will be  1/f=1/v+1/u

1/-10=1/-20+1/u

2/u=1/-10+1/20

1/u=(-20+10)/200

1/u = (-10)/200

1/u=-1/20

u=-20 cm

Therefore, the object should be placed at a distance of 20 cm from the mirror to form a real image.

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Solution At What Distance from a Concave Mirror of Focal Length 10 Cm Should an Object Be Placed So That: Its Real Image is Formed 20 Cm from the Mirror? Concept: Reflection of Light - Image Formation by Spherical Mirrors - Concave Mirror.
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