Standing wave in pipe has 4 antinodes, spanning 4 half-wavelengths Steps:

• Identify boundaries: closed end is node, open end is antinode for displacement wave.
• Count pattern: 4 nodes and 4 antinodes indicate 4 full half-wavelength segments (alternating N-A pairs).
• Relate to length: pipe length L = 4 × (λ/2) = 2λ.
• Solve: 2m = 2λ, so λ = 1m.

Why B is correct:

• Matches formula for standing wave where number of antinodes equals number of half-wavelengths in L, giving λ = L/2 = 1m.

Why the others are wrong:

• A: λ=0.5m implies L=4λ (8 half-waves), requiring 8 antinodes, exceeds given 4.
• C: λ=1.5m implies L ≈ 1.33λ (2.67 half-waves), requiring ~3 antinodes, not 4.
• D: λ=1.6m fits 5th harmonic (L=5λ/4), with only 2 nodes and 2 antinodes inside, not 4.

Final answer: B