in a concave mirrior an object is placed at distance x from focus what will be the ratio of the size of image to the size of obj? answer in detail plz.
Answers
Answer:
In a concave mirror, an object is placed a distance d
1
from the focus and the real image is formed at a distance d
2
from the focus.
To find the focal length of the mirror
Solution:
Let the focal length of the concave mirror be f
And as the image formed is real, the object distance and image distance have same sign convention.
According to the given criteria,
Object distance, u=f+d
1
Image distance, v=f+d
2
Now by applying mirror formula, we get
f
1
=
v
1
+
u
1
⟹
f
1
=
vu
v+u
⟹vu=f(v+u)
Substituting the values of v and u, we get
(f+d
2
)(f+d
1
)=f(f+d
2
+f+d
1
)
⟹f
2
+fd
1
+fd
2
+d
1
d
2
=2f
2
+fd
1
+fd
2
⟹2f
2
−f
2
=d
1
d
2
⟹f
2
=d
1
d
2
⟹f=
d
1
d
2
is the required focal length of the concave mirror.
Explanation:
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Explanation:
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