A lamp emits lights X and Y of different frequencies, The frequency of X is 6.25×10^14. Light from the lamp is incident normally on a plane transmission grating (3500 lines per cm)
a) Find the wavelenght of light X in a vacuum.
b) An interference pattern is observed on the screen 0.4 m away from the grating but the fringes are not evenly distributed. In some regions on the screen, there are overlapped fringes.
i) Suggest one region where the fringes are overlapped.
ii) At the region where light X forms its 4th order fringe, overlapped fringe is observed. Find the location of the region.
iii) It is known that the wavelenght of light Y is between 600 nm and 650 nm. Estimate the value.