MHTCET 13 May 2023 Shift 2 Solved Paper

Since, the radius of curvature of both the surface is same,
‌∴‌‌‌

1

f

=‌

2(µ−1)

R

So, when one surface is made plane by grinding, we have
R1=R‌ and ‌R2=∞
Then, ‌

1

f′

=(µ−1)(‌

1

R

−0)
⇒‌‌‌

1

f′

=‌

(µ−1)

R

......(ii)
From Eqs. (i) and (ii), we get
So,
‌‌

f′

f

=2
‌∴‌‌f′=2f
and power will be ‌

P

2

. ‌‌(∵P=‌

1

f

)