In a concave lens, the focal length is considered to be: (2023)

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Question: In a concave lens, the focal length is considered to be: (2023)

Options:

Correct Answer: Negative

Exam Year: 2023

Solution:

The focal length of a concave lens is considered negative as it diverges light rays.

In a concave lens, the focal length is considered to be: (2023)

In a concave lens, the focal length is considered to be: (2023)

Step 1: Understand what a concave lens is. A concave lens is thinner in the middle and thicker at the edges.
Step 2: Know that a lens can bend light. A concave lens diverges (spreads out) light rays that pass through it.
Step 3: Learn about focal length. Focal length is the distance from the lens to the point where light rays meet (focus).
Step 4: Realize that for concave lenses, the light rays do not actually meet; they appear to come from a point behind the lens.
Step 5: Understand the convention used in optics. By convention, the focal length of a concave lens is assigned a negative value.
Step 6: Conclude that since a concave lens diverges light rays, its focal length is considered negative.

Focal Length of Lenses – The focal length of a lens is the distance from the lens to the focal point, with concave lenses having a negative focal length due to their diverging nature.
Lens Types – Understanding the difference between concave and convex lenses, where concave lenses diverge light and convex lenses converge light.