wiz-icon
MyQuestionIcon
MyQuestionIcon
3
You visited us 3 times! Enjoying our articles? Unlock Full Access!
Question

A convex lens forms a real image three times larger than the object on a screen. Object and screen are moved until the image becomes twice the size of the object. If the increase in distance of the object is 6 cm, the shift of the screen is:

A
36 cm
Right on! Give the BNAT exam to get a 100% scholarship for BYJUS courses
B
72 cm
No worries! We‘ve got your back. Try BYJU‘S free classes today!
C
18 cm
No worries! We‘ve got your back. Try BYJU‘S free classes today!
D
9 cm
No worries! We‘ve got your back. Try BYJU‘S free classes today!
Open in App
Solution

The correct option is A 36 cm
Let object and image distance be u and v respectively and focal length = f.
For the first case when magnification m=±3=vu
v=+3u image is real.
Using lens formula 1v1u=1f
13u+1u=1f
or 43u=1f ….. (1)

For the case when object distance is increased by 6 and m=±2=vu+6
v=2(u+6)
Using lens formula again,
12(6+u)+16+u=1f
or 32(6+u)=1f ….. (2)
Eqs. (1) and (2) gives
43u=32(6+u)
9u=48+8u
u=48 cm
Shift of screen = 3u – 2(6+u)
=3×482(6+48)
= 36 cm

flag
Suggest Corrections
thumbs-up
4
Join BYJU'S Learning Program
similar_icon
Related Videos
thumbnail
lock
Lens Formula, Magnification and Power of Lens
PHYSICS
Watch in App
Join BYJU'S Learning Program
CrossIcon