A convex lens is cut horizontally from the center into two equal parts. What is the focal length of each part?
A convex lens is cut horizontally from the center into two equal parts. What is the focal length of each part?
Explanation
When a convex lens is cut parallel to the principal axis (i.e., horizontally through the center):
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Each half becomes a smaller lens with the same curvature.
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Focal length remains unchanged because the shape (curvature) and refractive index are the same.
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Only the aperture (light-gathering area) is reduced.
So, even after cutting the lens horizontally, the focal length stays the same.