Light appears to travel in straight lines since

Light of wavelength $600 \,nm$ is incident normally on a slit of width $0.2 \,mm$. The angular width of the central maxima in the diffraction pattern is (measured from minimum to minimum):

In a diffraction experiment from a single slit, the angular width of the central maxima does $NOT$ depend upon

"The person standing behind the open door inside the room can hear the voice of the person standing on the other side of the door but they cannot see each other". Give an experiment based on the diffraction for this statement.

In a diffraction pattern produced by a thin wire,what happens to the fringe width when the diameter of the wire is increased?

Write the thoughts expressed by Richard Feynman regarding the difference between interference and diffraction.