A convex mirror of focal length 'f' forms an image that is 1/nth the size of the object.How far is the object from the mirror? A)f/n-1 B)(n-1)f C)(n-1/n)f D)nf-1.Please explain.

Dear student

Given that Magnification m = -v/u

 

so n = -v/u

that is, v = -nu

In the mirror equation

1/f = 1/v + 1/u

substituting for v

we get

1/f = 1/u - 1/nu

 

solving

 

1/f = (n-1)/nu

 

(n-1)f = nu

u = (n-1)f / n

 

so u = (1-1/n)f

so correct option is C.

 

We hope that clarifies your query

 

Regards

Team

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