Answer & explanation
Correct answer: option 2
Fringe width $\beta = \frac{\lambda D}{d} = \frac{6.5 \times 10^{-7}}{10^{-3}} = 0.65 mm$
Distance of $5^{th}$ bright fringe from $3^{rd}$ dark fringe is $\frac{5\lambda}{2}= 1.63 mm$
Correct answer: option 2
Fringe width $\beta = \frac{\lambda D}{d} = \frac{6.5 \times 10^{-7}}{10^{-3}} = 0.65 mm$
Distance of $5^{th}$ bright fringe from $3^{rd}$ dark fringe is $\frac{5\lambda}{2}= 1.63 mm$