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

An object is placed at a distance of 40 cm from a concave mirror of focal length 15 cm. If the object is displaced through a distance of 20 cm towards the mirror, the displacement of the image will be :

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

The correct option is B 36 cm away from the mirror
Given that,
Focal length of the mirror, f=15 cm (concave mirror)
Initial position of the object, u1=40 cm (concave mirror)


Let, when the object is at u1 image is formed at v1.
From mirror formula,
1v1+1u1=1f
1v1+1(40)=1(15)
1v1=140115=38120
v1=24 cm

When object is displaced 20 cm towards mirror,
u2=(4020)=20 cm
Using mirror formula,
1v2=120115=3460=160
v2=60 cm
Hence, displacement of image,
Δv=v2v1=60(24)
Δv=36 cm
Thus, image has shifted in -ve direction i.e., away from mirror along principal axis.

flag
Suggest Corrections
thumbs-up
0
Join BYJU'S Learning Program
similar_icon
Related Videos
thumbnail
lock
TIR Applications
PHYSICS
Watch in App
Join BYJU'S Learning Program
CrossIcon