A progressive wave of amplitude a a\,a has intensity III. This wave combines with another wave of amplitude 0.4a 0.4a\,0.4a at a point in space. The phase difference between the waves is 180∘180^\circ180∘.
What is the resultant intensity of the combined waves in terms of III?
0.16I0.16I0.16I
0.36I0.36I0.36I
0.6I0.6I0.6I
1.96I1.96I1.96I
