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For JEE wave problems, the approach depends on the sub-topic:

Progressive waves: Extract $A$, $k$, $\omega$ from the equation. Speed $= \omega/k$. Direction from the sign between $kx$ and $\omega t$ (minus = +x). Particle velocity = $\partial y/\partial t$.

Standing waves / pipes: Draw the boundary conditions first. Mark nodes (N) at fixed/closed ends and antinodes (A) at free/open ends. Count the loops to determine which harmonic. Apply the correct formula: strings/open pipes use $nv/(2L)$; closed pipes use $(2n-1)v/(4L)$. Always distinguish overtone number from harmonic number.

Beats: List both possible frequencies ($f \pm n$). Use loading/filing/tension change to resolve ambiguity. Track whether beats increase or decrease when the unknown frequency changes.

Doppler: Write the formula $f' = f(v \pm v_o)/(v \mp v_s)$. Determine signs by physical reasoning: approaching = higher frequency. Convert all speeds to m/s. For reflection problems, apply Doppler twice (incoming and reflected).

Common pitfalls: using the open pipe formula for closed pipes, forgetting end correction, wrong Doppler sign convention, confusing overtone and harmonic numbers, and not converting km/h to m/s.