JEE Advanced2012PhysicsWaves and SoundActual
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,
Options
- Aa high-pressure pulse starts travelling up the pipe, if the other end of the pipe is open.
- Ba low-pressure pulse starts travelling up the pipe, if the other end of the pipe is open.
- Ca low-pressure pulse starts travelling up the pipe, if the other end of the pipe is closed.
- Da high-pressure pulse starts travelling up the pipe, if the other end of the pipe is closed.
Correct answer
B. a low-pressure pulse starts travelling up the pipe, if the other end of the pipe is open.
Step-by-step solution
When a sound pulse is reflected from open end of a pipe, phase changes by 180^ . A high pressure pulse i.e., compression is reflected as a low pressure pulse i.e., rarefaction. When sound pulse is reflected through a rigid boundary (closed end of a pipe), no phase change occurs so a high pressure pulse is reflected as a high pressure pulse.