Question

In $YDSE$ how many maxima can be obtained on the screen if wavelength of light used is $200nm$ and $d=700nm$.

• A. $12$
• B. $7$
• C. $18$
• D. $Noneofthese$

Answer 1

The correct option is B $7$

$Giventhat\lambda =200nm,d=700nm\theta =\frac{\lambda }{d}Weknowthatmaximumanglecanbe{90}^0.Noofringsthatcanbeobtainedsayn,\left(n\right)=\frac{sin90}{sin\theta }=\frac{1}{sin\theta }If\theta issosmallthen-n=\frac{1}{\theta }=\frac{d}{\lambda }=\frac{7}{2}Noofmaxima=2n=2\times \frac{7}{2}=7$