Two sources of sound of the same frequency produce sound intensities `I` and `4I` at a point `P` when used individually. If they are used together such that the sounds from them reach `P` with a phase differenceof `2pi//3`, the intensity at `P` will be
A. 2l
B. 3l
C. 4l
D. 5l
A. 2l
B. 3l
C. 4l
D. 5l
Correct Answer – B
`I=I_(1)+I_(2)+2sqrt(I_(1)I_(2))cosphi`
`=I+4I+2sqrt(Ixx4I)xx”cos”(2pi)/3`
`=5I+4Ixx(-1/2)=5I-2I=3I`