The colour of light is characterised by which of the following characteristics?

The intensities of two coherent sources are $9I$ and $4I$. The intensity at a point where the path difference is $11\lambda$ is:

Two beams of light having intensities $I$ and $4I$ interfere to produce a fringe pattern on a screen. The phase difference between the two beams are $\pi/2$ and $\pi/3$ at points $A$ and $B$ respectively. The difference between the resultant intensities at the two points is $xI$. The value of $x$ will be.

Write the condition of destructive interference in terms of path and phase difference.

If the wavelength of light is $4000 \mathring A$,then the number of waves in $1 \ mm$ length will be

The two coherent sources of equal intensity produce a maximum intensity of $100$ units at a point. If the intensity of one of the sources is reduced by $36\%$ by reducing its width,then the intensity of light at the same point will be: