The fringe width for red colour as compared to that for violet colour is approximately

In case of Fraunhoffer diffraction at a single slit, the diffraction pattern on the screen is correct for which of the following statements?

When a compact disc (CD) is illuminated by small source of white light coloured bands are observed. This is due to

A slit of width $$a$$ is illuminated by red light of wavelength $$6500 \mathop A\limits^o$$. If the first diffraction minimum falls at $$30^{\circ}$$, then the value of $$a$$ is