Question

Consider sunlight incident on a slit of width `10^(4) Å` . The image seen through the slit shall
A. be a fine sharp slit white is 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

Correct Answer - A
(a) Given, width of the slit `=10^(4)` Å
`=10^(4)xx10^(-10)m=10^(-6) m=1 mu m`
Wavelength of ( visible ) sunlight varies from 4000Å to 8000Å.
As the width of slit is comparable to that of wavelength, hence diffraction occcurs with maxima at centre. So, at the central all colours appear i.e., mixing of colours form white patch at the centre.