What is the effective distance between the source of light and the screen in Fraunhofer Diffraction?a)Focal length of the convex lensb)Less than Focal Length of the convex lensc)Greater than the focal length of the convex lens and less than infinited)InfiniteCorrect answer is option 'D'. Can you explain this answer?

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Answer

The effective distance between the source of light and the screen in Fraunhofer Diffraction is infinite. This means that the screen is placed at a very large distance from the source of light.

Fraunhofer diffraction is a type of diffraction that occurs when the light waves passing through an aperture or around an object are analyzed at a distance far away from the aperture or object. In this case, the light waves are considered to be nearly parallel, and the diffraction pattern can be observed on a screen that is placed at a large distance from the source of light.

The reason why the effective distance is infinite can be understood by considering the properties of a convex lens. A convex lens converges the light rays that pass through it to a focal point. The distance from the lens to the focal point is called the focal length. When the screen is placed at a distance less than the focal length of the convex lens, the light rays will converge and form an image on the screen. However, in Fraunhofer diffraction, we want to observe the diffraction pattern, which is caused by the interference of the diffracted light waves.

If the screen is placed at a distance greater than the focal length of the convex lens, the light rays will be nearly parallel when they reach the screen. This is the condition required for observing the diffraction pattern. Placing the screen at a large distance allows the light waves to spread out and interfere with each other, resulting in the formation of the diffraction pattern.

In summary, the effective distance between the source of light and the screen in Fraunhofer Diffraction is infinite because the screen needs to be placed at a distance greater than the focal length of the convex lens to observe the diffraction pattern.

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