194. In the figure of a U-tube, the frequency is $680$ Hz and the cross-sectional area of the tube in each branch is one square centimeter. If the speed of sound propagation in the medium is $340\,\dfrac{\text{m}}{\text{s}}$, and resonance is to be achieved inside the tube, which of the following actions is appropriate?
[Figure: U-tube with two vertical branches, height labeled $65\,\text{cm}$, with water at the bottom]
(1) Pour $2.5$ cubic centimeters of water into one of the tubes. (2) Pour $5$ cubic centimeters of water into one of the tubes. (3) Remove $2.5$ cubic centimeters of water from the tube. (4) Remove $5$ cubic centimeters of water from the tube.
\textbf{194.} In the figure of a U-tube, the frequency is $680$ Hz and the cross-sectional area of the tube in each branch is one square centimeter. If the speed of sound propagation in the medium is $340\,\dfrac{\text{m}}{\text{s}}$, and resonance is to be achieved inside the tube, which of the following actions is appropriate?
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\textit{[Figure: U-tube with two vertical branches, height labeled $65\,\text{cm}$, with water at the bottom]}
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(1) Pour $2.5$ cubic centimeters of water into one of the tubes.
(2) Pour $5$ cubic centimeters of water into one of the tubes.
(3) Remove $2.5$ cubic centimeters of water from the tube.
(4) Remove $5$ cubic centimeters of water from the tube.
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