QUESTION 2 Q 2(a)(i) [TOTAL MARKS: 33] [6 Marks] In a standard Young's slits experiment, derive, with the aid of a schematic diagram, the following relationship describing the position of the intensity maxima: nλ = a.sin(0) where a is the slit separation, & is the wavelength and is the angular position of the point on the viewing screen. Q 2(a)(ii) [7 Marks] In the case of a Young's slits experiment using a dual wavelength source, with spectral lines at 440 nm and 550 nm, and a slit separation of 40 μm, at what angular position (apart from 0=0°) will the intensity maxima of both lines coincide perfectly for the first time? Compute, for each spectral line, the corresponding interference order for this condition. Q 2(b) [10 Marks] Explain the term coherence, and in your answer distinguish between spatial and temporal coherence. For a Young's slits experiment explain, with the aid of a diagram, why an extended source leads to a reduction in the interference fringe visibility. Q 2(c) [10 Marks] An experimental set-up using Young's double slits, in which diffraction effects may be ignored, is shown in the figure below. It consists of an ideal point source 'S' (i.e. monochromatic (wavelength 2), fully coherent, natural light), two slits ('S1' and 'S2) equidistance from 'S' and separated by a distance 'a', and a screen located a distance 's' from the slits (with the centre marked '0'). Two optics holders (H1' and 'H2) are located in front of the slits 'S1' and 'S2', respectively, such that they do not block, or affect in any way, light entering the slits when empty. S H1 $1 52 H2 Screen