focus-1

Q1.) in convex lens distance of an object from focus : 8 cm. its image distance from focus : 8 cm. find the focal length

16 Answers

1
The Scorpion ·

For covex lens...

1/f = 1/s1 + 1/s2

=> 1/f = 1/8 + 1/8

=> f= 4cm...

if there's any hidden complexity in dis problem, then let me know dat... thanq...

1
rahul wadhwani ·

your answer is wrong think again

1
Honey Arora ·

it shd be f=8cm

1
abhi91_sa ·

use proper sign conventions...u and f are -ve...

1
rahul wadhwani ·

think once plz again yaar u r again wrong

1
rahul wadhwani ·

hey reply plzz anyone yaar

1
Honey Arora ·

tk u=-(8+f),v=8+f and solve

11
Subash ·

1/(8-f)-1/-(f+8)=1/f

is this correct

u have to consider that the distances are from the focus and not from the pole and also sign convention

this is some what simple na

1
Honey Arora ·

u r using mirror formula..........

1
rahul wadhwani ·

your ans =8 is correct if u will see form newton formula but u have forget tat f also depend on medium in which it is kept so nothing can be said as i had not mentioned the medium in which it is kept

11
Subash ·

@ honey thanx i have corrcted it

1
voldy ·

f=8 cm
newton's formula.

1
rahul wadhwani ·

hey srinath if medium has same RI then wat will happen

1
abhijeetkumar kumar ·

i am getting 8(√2-1) as the focus taking medium as air!!

1
abhijeetkumar kumar ·

but if talking about the medium!
let the thickness of the bi convex lens is =t

then distance b\w object and imagege = 8 - t + ( r.i * t)

and distance b\w focus and image =8

where r.i is the refractive index of the glass!!

1
rahul wadhwani ·

hey abhijeet give explanation & proof plz

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