Practicing Success

Target Exam

CUET

Subject

Physics

Chapter

Ray Optics

Question:

A convex mirror of focal length f forms an image which is 1/n times the object. The distance of the object from the mirror is : 

Options:

(n-1) f

\(\frac{n-1}{n}\) f 

(n+1) f

\(\frac{n+1}{n}\) f 

Correct Answer:

(n-1) f

Explanation:

$ m = \frac{1}{n} = -\frac{v}{-u}$

$ v = \frac{u}{n}$

Mirror Equation 

$\frac{1}{v} + \frac{1}{u} = \frac{1}{f}$

$ \frac{n}{u} + \frac{1}{-u} = \frac{1}{f}$

$\Rightarrow u = (n - 1)f$