Draw a graph showing the variation of intensity with angle in a single slit diffraction experiment.

The general expression for the path difference $\lambda$ in case of a single slit diffraction experiment for small angle $\theta$ is given as,
  $\sin \theta =\theta =\frac{n\lambda }{a}$
where, $n$ is an integer.
The above expression shows that the intensity of the central maxima is maximum and it goes on decreasing as the order of maxima increases. That is when angle of diffraction is 0 degree then the waves coming from all points from the slits arrive on the screen with the same phase which results in the maximum intensity at the centre of the screen. And as the angle of diffraction increases there is variation in the intensity that is intensity goes on decreasing with the increase in angle of diffraction.

Following figure shows the variation of intensity with respect to the angle in a single slit diffraction experiment: