Question

A man wants to get a picture of a zebra. He photographed a white donkey after fitting a glass, with black stripes on to the lens of his camera. What photo will he get?

Answer 1

Hint: We need to know what happens when a part of the lens is darkened out. That is when an object’s image is tried to be found when a part of the lens is darkened a complete image of the object is still formed on the end and this image is exact replica of the same object, however the image is hazy and of less intensity as compared to the image created when the lens was clear.

Step by step solution:
Let’s start by understanding what happens when a glass with black opaque strips are put on the objective lens of the camera while taking a picture.
Let’s consider a case, when light rays pass through a lens having half of it blacked out. For such a case, the image produced isn’t half of the object, since half of the lens was blacked out but, instead a full image of the object is prepared. However, the kind of image isn’t as sharp and bright as it would have been if the whole lens was clear.
Similarly, when the block of glass fitted with black stripes is put on the objective lens and an image of the white donkey is clicked, using this system, the image will still be as that of a white donkey. However, this image of the white donkey will be much less intense and hazy as compared to the one when the objective lens would have been clear and transparent.

Note: To understand what happens when light rays pass through a grid of opaque substance. Let’s consider the opaque grid to be painted in black to ensure that no reflection takes place. When, the grid is placed outside in bright sunlight. The sun’s rays can be considered to be parallel, as the rays emerging from the sun come from so far that it can be considered to be emerging from infinity. When these rays pass through the grid, they throw their shadow when we move the screen where the shadow is being cast further back, we will see the shadow diminishes gradually and the sunlight seems to be appearing again. However, the intensity of the sunlight diminishes based on how close spaced are the grids as compared to the intensity of sunlight when not being passed through the grid at the same distance.