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 lights is $6000A^0$, then wavelength of the other light wave corresponding to the maximum will be ;

• A. $3300A^0$
• B. $4400A^0$
• C. $5500A^0$
• D. $6600A^0$

Answer 1

The correct option is B $4400A^0$

As we have learned

Fraunhofer Diffraction :- $b\sin \theta =n\lambda$

Where in condition of $n^{th}$ minima,

$b=$ slit width

$\theta =$ angle of deviation

For first maxima

$b\sin \theta =\frac{3\lambda }{2}⟶\left(1\right)$

For first minima of red light

$b\sin \theta ={\lambda }_{red}$

$\Rightarrow {\lambda }_{red}=\frac{3\lambda }{2}$

$\lambda =\frac{2\lambda }{3}red$

$=\frac{2}{3}\times 2200$

$=4400A^0$