Huygens construction: the new wavefront is the forward envelope of the waveletsहाइगेंस रचना: नया तरंगाग्र तरंगिकाओं का अग्र आवरण हैHuygens construction: the new wavefront is the forward envelope of the wavelets

NCERT Fig 10.2 · Class 12 Physics · Chapter 10 · interactive diagram

Parts and what they mean

• Point source O (बिंदु स्रोत O) — Centre of the spherical wavefronts.
• Wavefront F₁F₂ at t = 0 (t = 0 पर तरंगाग्र F₁F₂) — The known wavefront we start from.
• Points on the wavefront (तरंगाग्र के बिंदु) — Huygens: every point of a wavefront acts as a source of secondary disturbance.
• Secondary wavelets (द्वितीयक तरंगिकाएँ) — Spheres of radius vτ drawn from each point; they spread with the speed v of the wave.
• Radius vτ (त्रिज्या vτ) — In time τ each wavelet grows to radius vτ (v = speed of the wave in the medium).
• New wavefront G₁G₂ at t = τ (t = τ पर नया तरंगाग्र G₁G₂) — The common tangent (forward envelope) of all wavelets — again a sphere centred at O.
• Backwave D₁D₂ (पश्च तरंग D₁D₂) — The backward envelope does not exist. Huygens assumed wavelets have zero amplitude backwards; the rigorous wave theory justifies its absence.

Original diagram drawn by Simple Learning Hub, based on NCERT Fig 10.2. Report a mistake