Two open pipes of length L 1 and L 2 (L 1 2 ) are sounded together. Beats per second = 5. If fundamental freq of shorter is 100 Hz, L 2 /L 1 equals:

Two open pipes of length L 1 and L 2 (L…

Answer: 19/20.

A 0.95
B 20/21
C 19/20
D 21/20

Correct answer: C. 19/20

Explanation: f1=100, f2=f1-5=95. f2/f1=95/100=19/20. Since f=v/(2L), L proportional to 1/f. L2/L1=f1/f2=100/95=20/19. So L1/L2=19/20.

A standing wave forms from two identical waves travelling in opposite directions and interfering; nodes (always zero displacement) and antinodes (maximum displacement) stay fixed in place, unlike a travelling wave where the whole pattern moves.

Concept context

Wave types, superposition, standing waves, Doppler effect, and sound intensity.

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Two open pipes of length L<sub>1</sub> and L<sub>2</sub> (L<sub>1</sub> < L<sub>2</sub>) are sounded together. Beats per second = 5. If fundamental freq of shorter is 100 Hz, L<sub>2</sub>/L<sub>1</sub> equals:

Concept context

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