question_answer

If a balloon is filled with \[\text{C}{{\text{O}}_{2}}\] gas, then how will it behave for sound as a lens? What happens if \[\text{C}{{\text{O}}_{2}}\] gas is replaced \[{{H}_{2}}\] gas?

Answer:

                The velocity of sound in \[C{{O}_{2}}\] is less than that in air. Hence a balloon filled with \[C{{O}_{2}}\] will behave like a convex lens. But the velocity of sound in \[{{H}_{2}}\] is greater than that in air, so a balloon filled with \[{{H}_{2}}\] will behave like a concave lens.