[问答题]
A parallel beam of red light passes through two parallel slits with negligible width and an interference pattern is formed on a distant screen.
$θ$ is the angle that shows the diffraction angle of the light waves reaching any point on the screen.
1.Explain why an interference pattern is observed on the screen.
2.On the axes below, sketch a graph to show how the intensity I of light on the screen varies with angle $θ$.
(There is no need to add values to the axes)
3.In the arrangement, the red light source is replaced with a blue light source with the same intensity. How would the drawn graph in (a) (ii) differ?
