# Diffraction and interference of light

The objective of this experiment is to measure the wavelength of Sodium (Na) light using the property of diffraction of light; And to measure the Rydberg constant for hydrogen. In the first part of the experiment Na light was allowed to diffract through very small slits and the behavior of the diffracted light was examined by measuring the position of the bright lights. In the second part of the experiment hydrogen was allowed to diffract through very small slits and the behavior of each of the three bright lights was examined by measuring the position of each bright color. In the first part of the experiment the distance between the slits and the screen was 0.70m, two different distances between the lines of the grating (d) were used (1/100mm and 1/300mm) and the position of the first bright lights in each case were 0.04m and 0.12m respectively. In the second part of the experiment, the distance between the screen and the slits was 0.75m. When the distance between the slits was 1/300mm the positions of the red, blue-green, violet bright colors were 14cm, 11.5cm and 9.5cm. When the distance between the slits was 1/600mm the position of the red, blue-green, violet bright colors were 29.7cm, 21.5cm and 19cm.

In the first experiment the angle of diffraction was calculated using the formula tan θ = y/L to get θ = 3.27о and the wavelength (λ) was calculated using the formula d sin θ = n λ to get 5.7 X 10-7 and 5.63 X 10-7 when the distance between each slit was 1/100mm and 1/300mm respectively. The average wavelength of sodium is λNa = 5.65 X 10-7. The same formulas were used to calculate the wavelength in the second experiment to get λred = 6.12 X 10-7, λblue-green = 5.03 X 10-7 and λviolet = 4.19 X 10-7, λ when the distance between each slits was 1/300mm, and λred = 6.11 X 10-7, λblue-green = 4.69 X 10-7 and λviolet = 3.99 X 10-7 when the distance between each slit was 1/600mm, the average of the wavelength λred = 6.12 X 10-7, λblue-green = 4.86 X 10-7 and...