Question

An object is placed at a distance of 2.5 m from a convex lens of focal length 3 m. Its image will be

Answer 1

Answer:

The image will be imaginary and formed to 15 m behind to the lens.

Explanation:

Let,

u = object distance

v = image distance

f = focal length

Given,

f = 3m. Since, it is convex lens so, f (+ve)

and, u = 2.5 m

Then, v =?

we know,

$\frac{1}{u} + \frac{1}{v} = \frac{1}{f} \\ \frac{1}{v} = \frac{1}{f} - \frac{1}{u} \\ \frac{1}{v} = \frac{1}{3} - \frac{1}{2.5} \\ \frac{1}{v} = - \frac{1}{15} \\ v = - 15m$

so, the image will be formed behind to the lens at about the distance 15m.