Question

In Young's double slit experiment, fringes of width $\beta$ are produced on a screen kept at a distance of 1 m from the slit. When the screen is moved away by $5 \times 10^{-2}$ m, fringe width changes by $3 \times10^{-5}$ m. The separation between the slits is $1 \times10^{-3} m$. The wavelength of the light used is

• A. 500 nm
• B. 600 nm
• C. 700 nm
• D. 400 nm

Answer 1

The Correct Option is B

In YDSE, we have Wavelength $\lambda =\frac{\Delta \beta d}{\Delta D}=\frac{3 \times 10^{-5} \times 1 \times 10^{-3}}{5 \times 10^{-2}}$ $=6 \times 10^{-7} \,m$ or $\lambda=600 \,nm$