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:

5. Colours appear on a thin soap film and on soap bubbles due to the phenomenon of ?

4. Interference was observed in interference chamber where air was present, now the chamber is evacuated, and if the same light is used, a careful observer will see ?

3. Ratio of intensities of two waves are given by 4 : 1. Then the ratio of the amplitudes of the two waves is ?

2. Interference is possible in ?

1. Which one of the following phenomena is not explained by Huygens construction of wavefront?