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 towards the mirror
B.
36 cm away from the mirror
C.
30 cm away from the mirror
-
.
D.
36 cm towards the mirror
Answers
Answered by
1
Answer:
As we have learned
Mirror Formula -
frac{1}{v}+frac{1}{u}=frac{1}{f}
- wherein
u= Object distance from pole of mirror.
v= Image distance from pole of mirror.
f= focal length of the mirror.
u_{1}= -40cm
f= -15cm
\frac{1}{v_{1}}=\frac{1}{f_{1}}-\frac{1}{u_{1}}=\frac{-1}{15}+\frac{1}{40}=\frac{-8+3}{120}=\frac{-5}{120}
{v_{1}= -24cm
2nd case
{v_{2}}= -20cm
\frac{1}{v_{2}}=\frac{1}{f}-\frac{1}{u_{2}}=\frac{-1}{15}+\frac{1}{20}=\frac{-4+3}{60}
v_{2}=-60cm
Image gets displaced by 36 cm , away from the mirror
Option 1)
30 cm towards the mirror
This is incorrect
Option 2)
36 cm away from the mirror
This is correct
Option 3)nation:
Answered by
4
Answer:
B. 36cm away from the mirror.
Explanation:
- From the given question the image will be formed between F and CF .
- when the object is in 20cm the image will be formed beyond CF
Attachments:
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