Two sound waves (expressed in CGS units) given by y1=0.3 sin2πλ(vt−x) and y2=0.4 sin2πλ(vt−x+θ) interfere. The resultant amplitude at a place where phase difference is π2 will be
Resultant amplitude =√a21+a22+a1a2 cos ϕ
=√0.32+0.42+2× 0.3× 0.4× cosπ2=0.5 cm