Which is not the condition for the formation of echoes ?
A. Minimum distance between the source of sound and reflecting body should be 17 m.
B. The temperature of air should be above 20°C.
C. The wavelength of sound should be less than the height of the reflecting body.
D. The intensity of sound should be sufficient so that it could be heard after reflection.
Answer:A
Which is not the condition for the formation of echoes ?
A. Minimum distance between the source of sound and reflecting body should be 17 m. B. The temperature of air should be above 20°C. C. The wavelength of sound should be less than the height of the reflecting body. D. The intensity of sound should be sufficient so that it could be heard after reflection.