Question

One-half of a convex lens is covered with a black paper. Will this lens produce a complete image of the object? Verify your answer experimentally. Explain your observations.

Answer 1

Step 1. Requirement of the experiment

1. Convex lens
2. Candle
3. Two black sheets of paper

Step 2. Procedure

1. Place the lens on the table.
2. Light the candle and place it on one side of the lens.
3. Switch off all the lights in the room.
4. Take the black sheet and place it on the other side of the lens of the candle.
5. Now focus on the image formed on the sheet by moving the sheet and observe the image formed.
6. Now mark the position of the lens, candle and screen.
7. Now turn on the light and cover half of the lens with black paper and place the lens at the exact position and turn off the light.

Step 3. Observation

1. A focused image is obtained in both experiments.
2. The image formed by the half lens is less bright than the image formed by the full lens since a point on the object need two rays to form an image.
3. Since the entire lens is not covered so at least two rays pass through the lens and form the image.
4. But the number of rays involved is less so the image formed will be less intense and less bright.

Hence, the lens will produce a complete image of the object, but it will be less bright.