A beam of parallel rays is brought to focus by a plano-convex lens. A then concave lens of the same focal length is joined to the first lens. The effect of this is
a)
The focus shifts to infinity
b)
The focal point shifts towards the lens by a small distance
c)
The focal point shifts away from the lens by a small distance
d)
The focus remains undisturbed
A beam of parallel rays is brought to focus by a plano-convex lens. A then concave lens of the same focal length is joined to the first lens. The effect of this is
a)
The focus shifts to infinity
b)
The focal point shifts towards the lens by a small distance
c)
The focal point shifts away from the lens by a small distance
d)
The focus remains undisturbed
Question ID - 152352 | SaraNextGen Top Answer
A beam of parallel rays is brought to focus by a plano-convex lens. A then concave lens of the same focal length is joined to the first lens. The effect of this is
a)
The focus shifts to infinity
b)
The focal point shifts towards the lens by a small distance
c)
The focal point shifts away from the lens by a small distance
d)
The focus remains undisturbed
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A beam of parallel rays is brought to focus by a plano-convex lens. A then concave lens of the same focal length is joined to the first lens. The effect of this is |
|
|
a) |
The focus shifts to infinity |
|
b) |
The focal point shifts towards the lens by a small distance |
|
c) |
The focal point shifts away from the lens by a small distance |
|
d) |
The focus remains undisturbed |
|
(a) The combined focal length of plano-convex lens
Given,
Now when concave lens of same focal length is joined to first lens , then combined focal length
Thus, the image can be focused on infinity ( |
) or focus shifts to infinity.