1. In a Young’s double slit experiment, the slit separation is 0,20 mm and the distance of the screen from the double slit is 1,00 m
a. If the wavelength of light used is 644 nm, calculate the angle separation between two neighboring dark fringes on the screen when viewed from the double slit.
b. When the double slit is substituted with another, the fringes on the screen are just able to be resolved by the eye at the position double slit.
i) If the resolving power of the eye is 3.0 x 10-4 radians, what is the slit separation of the double slit.
ii) Using the double slit in b, explain what modification on the experimental set up that would enable the fringes on the screen to be seen clearly again. Give a quantitative example for your answer. If the screen is then moved further from double slit, describe the change to the fringe pattern.
2. A Young’s double slit system is fixed to one wall of an empty rectangular glass tank. A sodium vapor lamp with narrow slit is arranged behind the double slit so the interference rings are produced on the opposite wall of the glass tank. When the tank is filled with a type of oil, the fringe separation changes by 35 %.
a. Explain why and discuss whether the fringe separation increases or decreases.
b. Calculate the refractive index of the oil.
3. In a Young’s double slit experiment, monochromatic light of wavelength 500 nm produced an interference pattern on the screen. When a thin film of transparent material of refractive index 1,5 covers one of the slit, the central maximum is displaced to the position of the ninth bright fringe. Calculate the thickness of film.
4. In a Young’s double slit experiment, a light source that emits two different wavelengths of 7 x 10-7 m (red) and 5 x 10-7 m (green) is used. Show that fringes of the two colors exactly overlap for the first time rim the centre of the fringe pattern (n+1)/n = 5/4. What is the significant of n? What is the color of the ring at the point?
