Two coherent monochromatic light beams of intensities 4/ and 9/ are superimosed the maxmum and minimum possible intenties in the resulting beam are

Options

A. 3 I and 2 I
B. 9 I and 5 I
C. 16 I and 3 I
D. 25 I and I

Answer

D

Explanation

`I=I_(1)+I_(2)+ sqrt(I_(1)I_(2))2 cos (alpha_(1) alpha_(2))`
`:. I_("max")= 4I + 9 I + sqrt(4 I xx 9 I) 2 cos theta `
`= 12 I + 12 I =25 I`
`and I_("min") 4 I + 9 I + sqrt( 4 I xx 9 I) 2 cos pi =I`