wiz-icon
MyQuestionIcon
MyQuestionIcon
1
You visited us 1 times! Enjoying our articles? Unlock Full Access!
Question

When the object is at distance u1 and u2 the images formed by the same lens are real and virtual respectively and of the same size. Then the focal length of the lens is :

A
12u1u2
No worries! We‘ve got your back. Try BYJU‘S free classes today!
B
u1+u22
Right on! Give the BNAT exam to get a 100% scholarship for BYJUS courses
C
u1u2
No worries! We‘ve got your back. Try BYJU‘S free classes today!
D
(u1+u2)
No worries! We‘ve got your back. Try BYJU‘S free classes today!
Open in App
Solution

The correct option is C u1+u22
* by apply ing mirror formula in tooth the cases. 1V11(V1)=1f=(1)1(V2)1(u2)=1f=(2)
by applying magnification formula m=v1M2(5)m=V2u2
as maquification is same in both cases by sign of
V. \& U , are different in 1st case.
by eq (1) we can say v1=u1fu1f;(5)=v2=u2ffu2=(6) by (3) &(4v1μ1=v2u2 (7)
by equ (5), (6)(7) as v1x2=u1u2(u1fu1f)u2ffu2=u1u2
fu1fffu2=1
fu2=u1f
2f=u1+u2
f=u1+u22
Hence obtion B 's correct

2002654_1291881_ans_8dd88b98c409498983a622b7514e4772.PNG

flag
Suggest Corrections
thumbs-up
0
Join BYJU'S Learning Program
similar_icon
Related Videos
thumbnail
lock
Thin Lenses: Point Objects
PHYSICS
Watch in App
Join BYJU'S Learning Program
CrossIcon