Manipal Entrance Test 2020 Physics Paper

Given, power P=3D
f=‌

1

P

=‌

1

3

m=‌

100

3

cm
u=−25cm.
Applying lens formula, we can write
‌

1

v

−‌

1

u

=‌

1

f

⇒‌‌‌

1

v

+‌

1

25

=‌

3

100

v=−100cm
Now, again using lens formula we can write
‌

1

v

−‌

1

u

=‌

1

f

As, focal length of a far sighted person deceases
⇒‌‌‌

1

u

<‌

−1

100

−‌

10

17

=‌

−17−1000

1700

=‌

−1017

1700

⇒u>‌

1700

1000

≈−1.7=−1m (nearest option)