In a YDSE setup with slit separation $d$ and screen distance $D$, the …

Question

In a YDSE setup with slit separation $d$ and screen distance $D$, the wavelength of the light source is doubled while the slit separation is halved. The new fringe width compared to the original is:

Accepted Answer

C. Quadrupled

$\beta = \lambda D / d$. If $\lambda 	o 2\lambda$ and $d 	o d/2$, then $\beta_	ext{new} = (2\lambda) D / (d/2) = 4 \lambda D / d = 4\beta$. The fringe width becomes four times the original.

Answer

Same

Answer

Doubled

Answer

Halved