• # question_answer In Young's double experiment carried out with light of wavelength $\lambda =5000\,\overset{\text{o}}{\mathop{\text{A}}}\,,$the distance between the slits is 0.2 mm and the screen is at 200 cm from the plane of slits. The central maximum is at $x=0.$The third maximum will be at x equal to: A) 1.67 cm                      B)  1.5 cmC)  0.5 cm                       D)  5.0 cm

${{x}_{n}}=2n\left( \frac{D\lambda }{2d} \right)\therefore {{x}_{3}}=2\times 3\left( \frac{D\lambda }{2d} \right)$ $=\frac{3\times 200\times 5000\times {{10}^{-8}}}{0.2\times {{10}^{-1}}}=1.5\,cm.$ Hence, the correction option is [b].