Question

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

(A) A high-pressure pulse starts travelling up the pipe, if the other end of the pipe is open.

(B) A low-pressure pulse starts travelling up the pipe, if the other end of the pipe is open. 

(C) A low-pressure pulse starts travelling up the pipe, if the other end of the pipe is closed.

(D) A high-pressure pulse starts travelling up the pipe, if the other end of the pipe is closed.

Answer 1

Correct option (B,D)

Explanation:

 At the open end, the phase of a pressure wave changes by π radian due to reflection. At the closed end, there is no change in the phase of a pressure wave due to reflection.