Stating Huygens' principle of secondary wavelets, throw light on its success and failure. Draw the wavefront of light emerging from a convex lens due to a point source of light placed on its focus.
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Huygens' principle is used to explain the propagation of light waves, and it works successfully in most optical phenomena except in cases involving quantum mechanics.
Step 1: Huygens' Principle.
Huygens' principle states that every point on a wavefront of light can be considered as a source of secondary wavelets. The new position of the wavefront at any subsequent time is the envelope of these secondary wavelets. This principle helps explain phenomena such as reflection, refraction, and diffraction.
Step 2: Success of Huygens' Principle.
Huygens' principle successfully explains the propagation of light waves in terms of wavefronts and their movement over time. It is particularly useful in understanding diffraction and interference patterns.
Step 3: Failure of Huygens' Principle.
Huygens' principle fails when applied to the behavior of light in the presence of phenomena that require a more detailed understanding of the nature of light, such as the quantum theory of light or the photoelectric effect.
Step 4: Wavefront of Light from a Convex Lens.
When a point source of light is placed at the focus of a convex lens, the light emerging from the lens will form parallel rays. The wavefront of light emerging from the lens is a plane wavefront, as the lens focuses the light into parallel rays.
