A single slit of width a is illuminated by violet light of wavelength `400nm` and the width of the diffraction pattern is measured as y. When half of the slit width is covered and illuminated by yellow light of wavelength `600nm`, the width of the diffraction pattern is

Options

A. The pattern vanishes and the width is zero
B. `y//3`
C. 3y
D. None of these

Answer

C

Explanation

Width of central maxima = `y= (2lambdaD)/(d)`
`implies (y.)/(y)= (lambda.)/(d.) xx (d)/(lambda)= (600)/(d//2) xx (d)/(400)implies y.= 3y`