Consider the superposition of `N` harmonic waves of equal amplitude and frequency. If `N` is a very large number determine the resultant intensity in terms of the intensity `(I_(0))` of each component wave for the conditions when the component wave have identical phases.

Answer

`N^(2)I_(0)`

Explanation

`I_(0) = kA^(2)`
`y_(1) = A sin (wt - kx)`
`y_(2) = A sin (wt - kx)`
`y_(n) = A sin (wt - kx)`
`y_(r) = y_(1) + y_(2)"…….."+ y_(n)`
`y_(r) = NA sin (wt - kx)`
`I' = k(NA)^(2) = N^(2)I_(0)`