The wavelength of a stationary wave is 36.0cm. What is the distance between a node and the next anti-node?

Analyze the question: We're given the wavelength of a stationary (standing) wave and asked for the distance between a node and the next adjacent anti-node.

Concept: In a stationary wave:

• Distance between two successive nodes = λ/2
• Distance between two successive anti-nodes = λ/2
• Distance between a node and the next anti-node = λ/4

This is because a node and an anti-node sit half of a half-wavelength apart. Going from node to anti-node to node covers λ/2, so each step is λ/4.

Solution:

Distance = λ/4

= 36.0 cm ÷ 4

= 9.0 cm

Answer: B (9.0 cm)

Tip: Remember the pattern "N to N = λ/2, N to A = λ/4." Option C (18.0 cm) is the trap: it is the distance between two successive nodes (λ/2), so check whether the question asks for node-to-node or node-to-anti-node.