Question

a person cannot see distinctly only object places beyond 40 cm from his eye. Calculate the power of lens which will enable to see distinct clearly

Answer 1

Answer:

A lens which can bring an object at infinity to 40 cm is required here.

So u=∞ and v=−40cm

we know

f

1

=

v

1

−

u

1

f

1

=

−40

1

−

∞

1

So f=−40cm=−0.4m

Power of lens P=

f

1

=1/−0.4=−2.5D