A) 8 mm
B) 6 mm
C) 4 mm
D) 3 mm
Correct Answer: B
Solution :
Given \[{{\lambda }_{1}}=12000{\AA}\] and \[{{\lambda }_{2}}=10000{\AA},\] |
\[D=2\,cm\] and \[d=2\,mm=2\times {{10}^{-3}}cm\]. |
We have \[\frac{{{\lambda }_{1}}}{{{\lambda }_{2}}}=\frac{{{h}_{1}}}{{{h}_{2}}}\] |
\[=\frac{12000}{10000}=\frac{6}{5}\] |
as \[x=\frac{{{u}_{1}}{{\lambda }_{1}}D}{d}=\frac{5\times 12000\times {{10}^{-10}}\times 2}{2\times {{10}^{-3}}}\] |
\[=5\times 1.2\times {{10}^{4}}\times {{10}^{-10}}\times {{10}^{3}}=6mm\] |
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