Question

In an experiment of single slit diffraction pattern, first minimum for red light coincides with first maximum of some other wavelength. If wavelength of red light is $6000A^o$, then wavelength of first maximum will be

• A. $3000A^o$
• B. $4000A^o$
• C. $5000A^o$
• D. $6000A^o$

Answer 1

The correct option is B $4000A^o$

First Minima of red light coincides with maxima of some other light .
$(n+\frac{1}{2}){\lambda }_{unknown}=n{\lambda }_{red}$
${\lambda }_{unknown}=\frac{2}{3}\times 6000$
${\lambda }_{unknown}=4000A^o$