Two mutually coherent beams having parallel electric fields are described by with amplitud...

Two mutually coherent beams having parallel electric fields are described by

with amplitudes in kV/m. The beams interfere at a point P where the phase difference due to path is π/3 (the first beam having the longer path). At the point of superposition, calculate (a) the irradiances I1 and I2 of the individual beams; (b) the irradiance I12 due to their interference; (c) the net irradiance; (d) the fringe visibility.

Figure 1