One-half of a convex lens is covered with a black paper. Will this lens produce a complete image of the object? Verify your answers experimentally? Explain your observations.
Hint: Covering the top half of the convex lens blocks half of the incoming rays. We will use a convex lens, a lit candle, and a sheet of paper to test if a half-covered lens can produce a complete image of the object.
Complete step-by-step answer:
A single point on the object needs only two rays passing from the lens to form an image. Since the entire convex lens is not covered, at least two rays from each point of the object can still pass through the lens, allowing an image to form. However, because the coverage reduces the number of rays contributing to the image, the resulting image will be dimmer and less bright.
Experiment: To verify whether a half-covered convex lens can produce a complete image of the object.
Required Materials: A convex lens, a candle, and two pieces of black paper.
Procedure:
- Secure a convex lens on the table. Use a match to light a candle and position it next to one side of the lens. Turn off the lights to create a dark environment.
- Place the sheet of paper on the opposite side of the lens from the candle.
- Move the sheet of paper to focus the image produced by the lens.
- Observe the image carefully.
- Mark the positions of the candle, lens, and screen.
- Turn off the light and cover half of the convex lens with the second sheet of black paper.
- Place the lens back in its original position on the table and repeat the experiment.
Observations: A focused image of the candle is produced in both experiments. However, the image created with half of the lens covered is dimmer than when the lens is fully exposed.
Conclusion: Covering the top half of the lens blocks half of the incoming rays. The image is formed by the rays passing through the bottom half of the lens. This indicates that any section of the lens that includes part of both curved surfaces can still produce an image, albeit a dimmer one.
Note: Even with half of the convex lens covered, a complete image of the object will still be formed. However, the brightness of this image will be less compared to one created with a fully exposed lens. The lens’s shape does not affect the ability to form an image; it only impacts the brightness, provided that both curved surfaces are in line.