In Young’s double-slit experiment, the slits are separated by 0.28 mm and the screen is placed 1.4 m away. The distance between the central bright fringe and the fourth bright fringe is measured to be 1.2 cm. Determine the wavelength of light used in the experiment.

1. 600 nm
2. 500 nm
3. 400 nm
4. 200 nm

In a double-slit experiment the angular width of a fringe is found to be \(0.2^\circ\) on a screen placed \(1\) m away. The wavelength of light used is \(600\) nm. What will be the angular width of the fringe if the entire experimental apparatus is immersed in water?
(Take the refractive index of water to be \(4/3\)).
1. \(0.33^\circ\)
2. \(0.20^\circ\)
3. \(0.15^\circ\)
4. \(0.10^\circ\)

A beam of light consisting of two wavelengths, 650 nm, and 520 nm, is used to obtain interference fringes in Young’s double-slit experiment. What is the distance of the third bright fringe on the screen from the central maximum for wavelength 650 nm?
1. \(1950 \frac{\mathrm{D}}{\mathrm{d}} \mathrm{nm}\)
2. \(1700 \frac{\mathrm{D}}{\mathrm{d}} \mathrm{nm}\)
3. \(1100 \frac{\mathrm{D}}{\mathrm{d}} \mathrm{nm}\)
4. \(1861 \frac{D}{d} n m\)

In a double-slit experiment using the light of wavelength \(600\) nm, the angular width of a fringe formed on a distant screen is \(0.1^\circ.\) What is the spacing between the two slits?
1. \(3.44 \times 10^{-4} \) m
2. \(2.54 \times 10^{-4} \) m
3. \(1.31 \times 10^{-4} \) m
4. \(2.01 \times 10^{-4}\) m