Two sound waves moves in the same direction in the same medium. The pressure amplutides of the waves are equal but the wavelength of the first wave is double the second. Let the average power transmitted across a cross section by the first wave be `P_1` and that by the second wave be `P_2` then.
A. `P_1=P_2`
B. `P_1=4P_2`
C. `P_2=2P_1`
D. `P_2=4P_1`
