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

Coherent sources are characterized by the same

Consider the following statements about interference of light:
$A$. The interference fringes are equally bright and equally spaced.
$B$. At the centre of a bright fringe,the intensity is four times the intensity of the incident wave.
$C$. For constructive interference of two waves,the crest of one wave coincides with the trough of another wave.
Which of the above statements are correct?

Two light waves of intensities $I$ and $2I$ superimpose on each other. If the path difference between the light waves reaching a point is $12.5 \%$ of the wavelength of the light,then the resultant intensity at the point is (Both the light waves have same wavelength).

Two light beams of intensities $4\,I$ and $9\,I$ interfere on a screen. The phase difference between these beams on the screen at point $A$ is $0$ and at point $B$ is $\pi$. The difference of resultant intensities,at the points $A$ and $B$,will be $....I$.

An interference pattern is obtained with two coherent sources of intensity ratio $n:1$. The ratio $\frac{I_{\text{Max}}-I_{\text{Min}}}{I_{\text{Max}}+I_{\text{Min}}}$ will be maximum if