 According to Huygens' principle, every point on a wavefront acts as a source of:
ASecondary spherical wavelets
BMaterial particles
CPhotons
DElectrostatic field lines
Answer & Solution
Correct answer: A. Secondary spherical wavelets
Huygens' principle: each point on a wavefront acts as a fresh source of secondary spherical wavelets that spread out in all directions with the speed of the wave. The envelope of these wavelets at a later time gives the new wavefront. This geometric construction explains reflection, refraction, interference and diffraction without invoking the photon picture.
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