Question

In YDSE, if the separation between the slits is tripled and the distance between screen and slit plane is also tripled, then the fringe width

• A. Becomes half
• B. Remains unchanged
• C. Becomes one-third
• D. Gets tripled

Answer 1

The correct option is B Remains unchanged

In YDSE fringe width is given as

$\beta =\frac{\lambda D}{d}$, $d$ is distance between slits and $D$ is distance between screen and slit plane

${\beta }^{{}^{\prime }}=\frac{\lambda \left(3D\right)}{\left(3d\right)}=\frac{\lambda D}{d}=\beta$