Two mutually incoherent sources illuminate the same point on a screen. The intensities produced by the two sources separately at that point are 3I and 5I. What is the resultant intensity when both sources are present simultaneously?
Options

Question

Two mutually incoherent sources illuminate the same point on a screen. The intensities produced by the two sources separately at that point are 3I and 5I. What is the resultant intensity when both sources are present simultaneously?

Options

G1 Physics · Accepted Answer

For incoherent sources, the relative phase varies randomly with time. Hence the interference term averages to zero: I(resultant) = I₁+I₂ = 3I+5I = 8I. Correct option: B.