Question

The image when obtained from a concave lens of focal length f is magnified up to n times the size of the object. What is the distance of object from the lens?​

Answer 1

• Using the lens formula,

`(1)/(v) - (1)/(u) = (1)/(f)`

`\implies \: (u)/(v) - 1 = (u)/(f) \: \: \: ......(i)`

`\text{As} \: m = (v)/(u) = n \: \: \: \: \: \: \text{(given)}`

`\implies (u)/(v) = (1)/(n)`

`\text{Substituting the above values in Eq. (i), we get}`

`\implies [(1)/(n) - 1 ] = (u)/(f)`

`\implies \: u = [ (1 - n)/(n) ]f`

Hope This Helps :)!!!