NCERT Exercise 14.19 - Waves
Question: Conceptual questions: (a) Why can transverse waves not propagate in a gas? (b) Do longitudinal waves need a medium? (c) Can a mechanical wave exist in vacuum? (d) Can a transverse wave travel on a spring? (e) Can a standing wave exist on a string of infinite length?
Answer: (a) **No shear in gas**; (b) **yes, a medium**; (c) **no**; (d) **yes**; (e) **no** � requires reflection.
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