Wave Propagation
Pulse moves at speed v across the medium.
Key Notes
Wave propagation: disturbance travels through a medium, transferring energy WITHOUT transferring matter.
Particles oscillate locally; the WAVE PATTERN moves at v = ω/k = fλ.
Wave nature is preserved: same A, f, ω as it propagates (in non-dispersive, lossless medium).
Reflection at boundary: fixed end → inverted reflection. Free end → erect reflection.
Refraction: wave speed changes when entering a new medium ⇒ wavelength changes (frequency stays).
Diffraction: bending around obstacles or through apertures. Significant when aperture size ≈ wavelength.
Superposition: when two waves meet, displacements ADD (algebraic). Each then continues independently.
Wave equation: ∂²y/∂t² = v²·∂²y/∂x² — satisfied by any traveling-wave solution.
Formulas
Wave equation
Defining differential equation; v = speed.
Travelling wave (general)
Sum of forward and backward waves.
Wavelength in medium
When wave enters a new medium, v changes, λ changes, f stays.
Doppler-shifted frequency
Relative motion of source and observer changes apparent frequency.
Important Points
WAVE propagates; PARTICLES oscillate in place.
Energy and momentum travel WITH the wave. Matter does not.
f is invariant across media (set by source). v and λ change.
Superposition: linear waves add algebraically — basis of interference, beats, standing waves.
Reflection: fixed end inverts; free end doesn't.
Pulse / wave SHAPE may distort in dispersive media (where v depends on f); preserved in non-dispersive media.
Wave Propagation notes from sciphylab (also known as SciPhy, SciPhy Lab, SciPhy Labs, Physics Lab). Class 11 physics revision for JEE Mains, JEE Advanced, NEET UG, AP Physics 1/2/C, SAT, and CUET-UG.