Question

In Young's double slit experiment, if the distance between two slits is equal to the wavelength of used light. Then the maximum number of bright fringes obtained on the screen will be

• A. Infinite
• B. $3$
• C. $7$
• D. $5$

Answer 1

Answer: (B)

$3$

We know

$d\sin \theta =\pm m\lambda$

but $d=\lambda$

so $\sin \theta =\pm m\Rightarrow$maximum value of $\sin \theta =1$

$m=\pm 1$

so the maximum number of bright fringes $=3$

Central maxima and also on either side of central maxima that makes the total to be 3.