Question

What is the focal length of the convex lens used? Give reason to justify your answer.

Hint:

In ray diagrams for convex lenses, light rays diverging from an object parallel to the optical axis are refracted through the focal point on the opposite side.

Answer 1

- The lens formula, \[ \frac{1}{f} = \frac{1}{v} - \frac{1}{u} \], is used to find the focal length (\( f \)), where \( v \) is the image distance and \( u \) is the object distance.
- The image distance (\( v \)) increases as the object distance (\( u \)) decreases, as shown in the table.
- This indicates a converging (convex) lens. The object is beyond the focal length. Specific \( u \) and \( v \) values allow calculation of the focal length. The image's movement with changing object distance aligns with a positive focal length of a convex lens.