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Wave Optics formula sheet

Every formula in the Wave Optics chapter for JEE Main, with one line on when it applies. Topic 1 is open to everyone; sign in free to read all 19 and download the PDF.

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How we count: 7× asked means 7 past JEE Main questions in the PrepWiser bank needed that formula, and "last" is the latest year one appeared. ★ marks formulas asked 8 or more times.

Wavefronts and Huygens' principle

Wavefront shapes
2× asked, last 2026
A∝1r (spherical)A∝1r (cylindrical),A const (plane)\begin{aligned}&A\propto\frac1r\ (\text{spherical})\\&A\propto\frac1{\sqrt r}\ (\text{cylindrical}),\qquad A\ \text{const (plane)}\end{aligned}
Rays normal to the wavefront; I∝A2I\propto A^2. Point at a lens focus: plane wave out.
Refraction by Huygens
3× asked, last 2026
sin⁡isin⁡r=v1v2=λ1λ2=n2n1\frac{\sin i}{\sin r}=\frac{v_1}{v_2}=\frac{\lambda_1}{\lambda_2}=\frac{n_2}{n_1}
Frequency fixed: v=c/nv=c/n, λ=λ0/n\lambda=\lambda_0/n. Reflection: i=ri=r.

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17 more formulas in 4 topics

Interference and coherence, Young's double-slit experiment, Diffraction and resolving power and Polarisation. Read the first part free. Sign in free with Google to read the rest and download the PDF.

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Interference and coherence

  • Path and phase difference6×
  • Two coherent waves6×
  • Maximum and minimum intensity16×
  • Equal slits14×
  • Thin film2×

Young's double-slit experiment

  • Fringe width19×
  • Fringe positions12×
  • Thin sheet over one slit7×
  • Two wavelengths together5×
  • White light1×

Diffraction and resolving power

  • Single slit12×
  • Central maximum8×
  • Fringes inside the envelope2×
  • Resolving power3×

Polarisation

  • Malus's law8×
  • Several polaroids7×
  • Brewster's law6×

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About 135 past JEE Main questions from this chapter, with instant answer checking and step-by-step solutions where available. Free, and you can start without signing up.

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Version 1, October 2026. Free to share for study, as it is. Please don't sell it or remove the PrepWiser name.

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