Question

a convex lens of focal length f produces a real image of size m times the size of object then object distance is​

Answer 1

Explanation:

Given,

Focal length =f

magnification, m=

n

1

We know,

m=

u

v

−

n

1

=

n

v

u=−nv.....(1)

from lens formula

f

1

=

v

1

−

u

1

=

v

1

+

nv

1

=

v.nv

nv+v

=

v(nv)

v(n+1)

⇒

f

1

=

n

f(n+1)

.....(2)

from (1) and (2)

u=−n

n

f(n+1)

u=−f(n+1)