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.
Yes, the lens will produce a complete image of the object. To verify this experimentally, take a convex lens and place a burning candle beyond 2F₁ on one side. Obtain a clear sharp image on a screen placed on the opposite side. Now, cover one-half of the convex lens with black paper and observe the image formed on the screen.
It is observed that a complete image of the object is still formed on the screen. The position and nature of the image remain the same as before. However, the brightness of the image is reduced compared to the image formed by the uncovered lens.
This happens because light from every point of the object can still pass through the uncovered portion of the lens. The image formation depends on refraction of light through the lens. Covering half the lens only reduces the amount of light passing through, resulting in a less bright but complete image.
Explanation
This question tests the understanding that image formation by a lens depends on the principle of refraction, not on the amount of lens surface available. When half the lens is covered, light rays from every point of the object still pass through the uncovered half and converge to form a complete image. The experimental verification follows the procedure outlined in Activity 9.12, where students place objects at various positions relative to F and 2F to study image formation. The key observation is that the image remains complete but becomes less bright due to reduced light intensity.