Question

distance between the middle of the lens and the focal point is called the
○ focal point
○ focal length
○ optical center
○ convex lens

Explanation:

To solve this, we analyze each option:

• Focal Point: A point, not a distance. Eliminate.
• Focal Length: Defined as the distance between the lens's middle (optical center) and the focal point. This matches the description.
• Optical Center: The middle of the lens, not a distance. Eliminate.
• Convex Lens: A type of lens, not a distance. Eliminate.

Answer:

B. Focal Length (assuming the options are labeled A, B, C, D with "Focal Length" as option B; adjust identifier if needed based on original labeling)