Question

An object is situated at 8 cm from a convex lens of focal length 10 cm. Find the position and nature of image. 3 points

Answer 1

Explanation:

Before solving this type of problems we hace to be familiar with the lens formula, that is,

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

where v= distance of the image from lens, u= distance of the object from the lens and f= focal length of the lens.

Putting u=-8 cm(as object will be at the right side of the lens) and f= 10 cm (focal length of a convex lens is always positive)

$\frac{1}{v} - ( \frac{1}{ - 8} ) = \frac{1}{10}$

$\frac{1}{v} = \frac{1}{10} - \frac{1}{8}$

$\frac{1}{v } = \frac{4 - 5}{40}$

$\frac{1}{v} = \frac{ - 1}{40}$

$v = - 40$

Image will form 40 cm away from the lens on the same side of the lens, hence it is virtual and erect.