Name: Rules for Ray Diagram
Uploaded: 2019-07-19
Duration: 6 min 12 s
Description: What are the basic rules of the ray diagram? A ray passing through the focal point on the way to a mirror will get reflected and travel parallel to the princ...

Question

A convex mirror has a focal length of $18 cm$ . The image of an object kept in front of the mirror is half the height of the object. What is the distance of the object from the mirror?

Accepted Answer

Given:

Focal length, $f = 18 cm$

Height of the image, $h_{i} = \frac{h_{o}}{2}$

Object distance, $u = ?$

We know that magnification is the ratio of height of the image to the height of the object. We also know that magnification in terms of distance, it is the ratio of image distance to the object distance.

$\frac{h_{i}}{h_{o}} = \frac{1}{2} = - \frac{v}{- u}$ (Since object is always kept to left side of mirror hence u is negative)

$\frac{v}{u} = \frac{1}{2} v = \frac{u}{2}$

By using Mirror Formula

$\frac{1}{f} = \frac{1}{u} + \frac{1}{v} \frac{1}{18} = \frac{1}{- u} + \frac{2}{u} \frac{1}{18} = \frac{- 1 + 2}{u} \frac{1}{18} = \frac{1}{u} u = 18 cm$

Hence, the distance of the object from the mirror is $18 cm$ .

A convex mirror has a focal length of $18 cm$ . The image of an object kept in front of the mirror is half the height of the object. What is the distance of the object from the mirror?

Important Questions on Reflection of Light

Learn and Prepare for any exam you want !

A convex mirror has a focal length of 18 cm. The image of an object kept in front of the mirror is half the height of the object. What is the distance of the object from the mirror?

Important Questions on Reflection of Light

Learn and Prepare for any exam you want !

A convex mirror has a focal length of $18 cm$ . The image of an object kept in front of the mirror is half the height of the object. What is the distance of the object from the mirror?