Question

a concave lens of focal length one metre is placed at a distance of 1 metres from an object where and at what distance will the image be formed​

Answer 1

Answer:

$\large\boxed{\sf{-0.5\;m}}$

Explanation:

Given, a concave lens.

We know that , focus of the concave lens lies on the left side of optical center.

Therefore, we have,

• focal length, f = - 1 m

Also, Object is placed on left side of the optical centre

Therefore, we have,

• Object distance, u = - 1 m

Now, let the image distance is ‘v’

By lens formula, we get,

$\large \boxed{ \red{\frac{1}{v} - \frac{1}{u} = \frac{1}{f} }}$

Putting the respective values, we get,

$= > \frac{1}{v} - \frac{1}{( -1 )} = \frac{1}{( - 1)} \\ \\ = > \frac{1}{v} + 1= - 1 \\ \\ = > \frac{1}{v} = - 1 - 1 \\ \\ = > \frac{1}{v} = - 2 \\ \\ = > \sf{ v = \frac{ - 1}{2} \: m}$

°.° Image distance is negative

.°. Image will be formed to the left side of the optical centre at a distance of 0.5 m from optical center towards left side.