Wave Optics

In Young's double slit experiment, the intensity at a point where the path difference is \(\frac{\lambda}{4}\) [ \(\lambda\) is wavelength of light used] is '\(\mathrm{I}\)'. If '\(\mathrm{I}_0\)' is the maximum intensity then \(\frac{\mathrm{I}}{\mathrm{I}_0}\) is equal to \(\left[\cos \frac{\pi}{4}=\sin \frac{\pi}{4}=\frac{1}{\sqrt{2}}\right]\)