Question

Consider sunlight incident on a slit of width $104A^o$. The image seen through the slit shall

• A. be a fine sharp slit white in colour at the Centre
• B. a bright slit white at the centre diffusing to zero intensities at the edges
• C. a bright slit white at the centre diffusing to regions of different colours
• D. only be a diffused slit white in colour

Answer 1

Answer: (A)

be a fine sharp slit white in colour at the Centre

The wavelength of the visible light lies in the range $4000A^o-7000A^o$ whereas the width of the slit is about $104A^o$. Since the width of the slit is comparable to that of wavelength. Diffraction occurs with maxima at centre.

The maxima consist of all the colour of lights present in the wave. Therefore, At the centre all colours appear i.e, mixing of colours from the white patch at the centre