6. The periodic waves of intensities I1 and I2 pass through a region at the same time in the same direction. The sum of the maximum and minimum intensities is:

6. The periodic waves of intensities I1 and I2 pass through a region at the same time in the same direction. The sum of the maximum and minimum intensities is:

(a) \( I_1 + I_2 \) 

(b) \(  (\sqrt{I_1} + \sqrt{I_2})^{2} \) 

(c) \(  (\sqrt{I_1} - \sqrt{I_2})^{2} \)

(d) \( 2 (I_1 + I_2) \)

Answer :  (d) \( 2 (I_1 + I_2) \)

\( I = I_1 + I_2 + 2\sqrt{I_1 I_2}\cos\phi \)

\( I_{\text{max}} = I_1 + I_2 + 2\sqrt{I_1 I_2}\cos 0^\circ \)

\( I_{\text{min}} = I_1 + I_2 - 2\sqrt{I_1 I_2}\cos180^\circ \)

\( I_\text{max}+I_\text{min} = 2 ( I_1 + I_2 ) \)