Question

Two coherent monochromatic light beams of intensities 4I and 9 I are superposed. The maximum and minimum possible intensities in the resulting beam are

• A. 13 I and 5 I
  
  
• B. 13 Iand 41 I
  
  
• C. 25 Iand I
  
• D. 9 I and 4 I

Answer 1

The correct option is C 25 Iand I


$I_{max}=(\sqrt{I_1}+\sqrt{I_2}{)}^2=(\sqrt{4I}+\sqrt{9I}{)}^2=25I$
$I_{min}=(\sqrt{I_2}-\sqrt{I_1}{)}^2=(\sqrt{9I}-\sqrt{4I}{)}^2$
$=(3-2)I$
$=I$