Question

person blows into open-end of a long pipe. As a result, a high­pressure pulse of air travels down the pipe. When this pulse reaches the other end of the pipe,

• A. a high­pressure pulse starts traveling up the pipe, it the other end of the pipe is open.
• B. a low­pressure pulse starts traveling up the pipe, if the other end ofthe pipe is open.
• C. a low­pressure pulse starts traveling up the pipe, if the other end ot the pipe is closed.
• D. a high­pressure pulse starts traveling up the pipe, if the other end of the pipe is closed.

Answer 1

Answer: (B), (D)

The correct options are
B a low­pressure pulse starts traveling up the pipe, if the other end ofthe pipe is open.
D a high­pressure pulse starts traveling up the pipe, if the other end of the pipe is closed.

[B, D] Pressure wave undergoes a phase-charge of $\pi$ rad on reflection from the open end and no phase change occurs on reflection from the closed end. Accordingly B, D is correct.