Practice question

**Wave addition** governed by phase difference determines resultant intensity ∝ A². Phase arises from path difference Δ = (2π/λ)·Δx, and resultant formula captures interference condition quantitatively for NCERT problems. The boundary conditions (e.g., fixed or free ends) determine where nodes (zero displacement) and antinodes (maximum displacement) occur by enforcing specific wave patterns. Using v = fλ and standing-wave condition fₙ = n v/(2L) or v/(4L) as applicable, calculation yields Boundary conditions, illustrating frequency-length-speed interdependence and quantization by boundaries.