Which characteristic of light determines its color?

Two coherent sources of intensities,$I_1$ and $I_2$ produce an interference pattern. The maximum intensity in the interference pattern will be

The frequency of a light wave with a wavelength of $500 \, \mathring A$ is $....... \, Hz$.

Two monochromatic and coherent point sources of light are placed at a certain distance from each other in the horizontal plane. The locus of all those points in the horizontal plane which have constructive interference will be

Two light sources are said to be coherent if they are obtained from

If two light waves reaching at a point produce destructive interference,then the condition of phase difference is: