Banner 0
Banner 1
Banner 2
Banner 3
Banner 4
Banner 5

Q.

Two thin lenses when in contact produce a combination of power +10 diopter. When they are 0.25 m apart, the power is reduced to +6 diopter. The respective power of the lenses in diopter are 

see full answer

Start JEE / NEET / Foundation preparation at rupees 99/day !!

21% of IItians & 23% of AIIMS delhi doctors are from Sri Chaitanya institute !!
An Intiative by Sri Chaitanya

a

5 each 

b

1 and 9

c

2 and 8

d

4 and 6

answer is B.

(Unlock A.I Detailed Solution for FREE)

Ready to Test Your Skills?

Check your Performance Today with our Free Mock Test used by Toppers!

Take Free Test

Detailed Solution

When in contact we have 

1F=1f1+1f2

10=1f1+1f2            P=1F=10

f1+f2=10f1f2  …….(1)

When at a separation of 0.25m we have, 

1F'=1f1+1f2-xf1f2

6=1f1+1f2-0.25f1f2

6=10-0.25f1f2

f1f2=116  …..(2)

From (1) we get, 

f1+f2=1016=58

Now, from (2) we get, 

f158-f1=116

16f12-10f1+1=0

16f12-8f1-2f1+1=0

8f12f1-1-12f1-1=0

8f1-12f1-1=0

f1=18 or f1=12

P1=8D or P1=2D

Hence the correct answer is (2).

Watch 3-min video & get full concept clarity

Best Courses for You

JEE

JEE

NEET

NEET

Foundation JEE

Foundation JEE

Foundation NEET

Foundation NEET

CBSE

CBSE

score_test_img

Get Expert Academic Guidance – Connect with a Counselor Today!

whats app icon