(a) A diffraction pattern is formed on a screen when a 0.4 mm slit is illuminated with 550 nm light. If the screen is 1.3 m away from the slit, calculate the fractional intensity (I/lo) at a point on the screen 3.9 mm away from the centre. (7 marks) (b) If you want to design a radio telescope with an angular resolution of 0.05 operating at a frequency of 94 GHz, what diameter should the radio telescope have? (6 marks) (c) (i) If a diffraction grating is illuminated with light from two spectral lines at 525.8 nm and 526.4 nm, calculate the minimum number of lines required to resolve the lines in the 2nd order spectrum. (ii) Calculate the slit spacing of a 1.2 cm grating with the minimum number of lines required to resolve these lines.